TLDR: The if part of present conditionals never takes a subjunctive form in present-day English, only an indicative one. You’re incorrectly trying to apply Portuguese rules for conditionals in English, but English does not work like Portuguese!
The examples you have presented are not grammatical in present day English because if clauses like the ones you’ve shown take a tensed verb:
The project she presented was a mess. If she *fail with another one she'll be fired.
That is ungrammatical. It needs to be like this:
The project she presented was a mess. If she fails with another one she'll be fired.
In the English of a far more ancient vintage than you will ever casually come across, we did at one point use a present subjunctive inflection there, and later an untensed infinitive, but that was long ago and for the most part far away.
Lusophone Excursions: For speakers of Portuguese only
- WARNING: To illustrate why this is wrong in a way the original poster can best understand it, I below show contrasting examples of the same sort of conditional in English and Portuguese. I also demonstrate that English has changed in its treatment of these over the best few hundred year, but that Portuguese has not. Lastly, I show that Spanish practice has split off from following the Portuguese practice to following the English one during that same period.
You seem to be attempting to “calque” Portuguese conditionals into English. Portuguese employs for these a special form which the Portuguese call the futuro do conjuctivo (future conjunctive) and the Brazilians futuro do subjuntivo (future subjunctive). These are not indicative forms in Portuguese the way they are in English and in Spanish:
- EN: If she fails at another project, she’ll be fired. —present indicative
- PT: Se ela falhar em outro projeto, (ela) será demitida. —future subjunctive
- ES: Si (ella) falla en otro proyecto, será despedida. —present indicative
The Portuguese would obviously* read ela falha not ela falhar there if it were in the indicative not the subjunctive, but this is not supposed to be indicative in Portuguese the way it is supposed to be in English. You’re trying to do the same thing in English, calquing the Portuguese conditional forms into English in ways that don’t make sense to native speakers of English. You should use the indicative in English here, just as speakers of your sister language Spanish now also do.
* “Obvious” to thee and to me, but probably to few other readers here.
Of Boys and Bulls: What happens when your raging bull gravely injures your neighbor
Once upon a time when the language was young, English actually did use a “modally marked form” (call it subjunctive if you must) there in its if clauses, but no longer. By way of example, please consider the following Early Modern English from the King James Version (KJV) of the Bible published in 1611. There we read for verse 29 from Exodus 21:
- [KJV] If an ox gore a man or a woman, that they die: then the ox shall be surely stoned, and his flesh shall not be eaten; but the owner of the ox shall be quit.
That’s what you’re trying to do, but we don’t do that any longer in English. Here’s how that same verse runs in the so-called “King James Version 2000” (KJV2000) translation:
- [KJV2000] If an ox gores a man or a woman, that they die: then the ox shall be surely stoned, and its flesh shall not be eaten; but the owner of the ox shall be clear.
So instead of “if an ox gore” in the Early Modern English, we now say “if an ox gores”. If you try to use the English of 400 years ago, particularly in ordinary conversation, most people will be confused and few will understand you correctly. They’ll think you’re making a mistake — which you would be. It would be just like speaking Portuguese today the way it was spoken back when Camõens wrote Os Lusíadas in the Sixteenth Century. You’d just confuse people.
For cultural comparison, here’s how that verse was translated into the Portuguese of its day by Antônio Pereira de Figueiredo a couple hundred years ago:
- [Pereira] Se hum touro ferir com as suas pontas hum homem, ou huma mulher, e elles morrerem isso, apedrejar-se-ha o touro, e não se lhe comerá a carne; mas o dono o touro será innocente.
Even though that uses the same inflections of its verbs as Modern Portuguese uses, it sure is funny to read and funny to say, isn’t it? The style of speaking and the words chosen have changed considerably as you will see when you compare what you have just now read above with two versions in Modern Portuguese (where the touro has become a boi :) as follows:
[O Livro] Se um boi escornear um homem ou uma mulher, tirandolhe a vida, o boi terá de ser apedrejado e não comerá a sua carne. Mas o dono do animal não será culpado de nada.
[NVI-PT] Se um boi chifrar um homem ou uma mulher, causando-lhe a morte, o boi terá que ser apedrejado até a morte, e a sua carne não poderá ser comida. Mas o dono do boi será absolvido.
So unlike English, Portuguese still uses a subjunctive there just as it did hundreds of years ago. But English does not. The English loss of the subjunctive there parallels the loss of the subjunctive in Spanish over the same period. Here’s how it ran in the Reina-Valera Antigua translation back when Spanish still used the future subjunctive for this sort of if clauses:
- [RVA] Si un buey acorneare hombre ó mujer, y de resultas muriere, el buey será apedreado, y no se comerá su carne; mas el dueño del buey será absuelto.
Even though that old sort of Spanish should be especially easy for Portuguese speakers to read because of its old words and old verb forms, people today no more talk that way in Spanish than they do in English. The Modern Spanish translation in the Castilian NIV runs:
- [CST] Si un toro cornea y mata a un hombre o a una mujer, se matará al toro a pedradas y no se comerá su carne. En tal caso, no se hará responsable al dueño del toro.
If as a Portuguese speaker you are going to speak English (or even Spanish) in a way that makes sense to native speakers of those other languages, you must shed your Lusophonic sensibilities about how present conditionals work and use only indicative forms not subjunctive ones in the if parts of these sorts of conditionals.
Postscript on calques and calquing
When you calque something from one language to another, you translate its original so literally that it risks losing its sense in the new language. Wiktionary says that a calque is:
A word or phrase in a language formed by word-for-word or morpheme-by-morpheme translation of a word in another language.
The Portuguese Wikipedia entry for that word starts out:
Em linguística, e mais precisamente em lexicologia, etimologia e linguística comparada, chama-se calque, calco ou decalque a um procedimento de formação de palavras que consiste em cunhar novos termos mediante a tradução de vocábulos estrangeiros e conforme as estruturas da língua de origem. É um tipo de empréstimo léxico particular, no qual o termo emprestado foi traduzido literalmente de uma língua para a outra, considerando mais a forma do que a ideia.