I would interpret your example as reading:
It will not be counted as a typo that would end up causing problems with your registration.
The implication is that a typo would trigger problems with your registration.
Structurally, this is a compound verb joined by a conjunction which is governed by a single subject: “It won’t X and Y”. Expanded in full, it’s two separate sentences that start out the same:
- It won’t be counted as a typo.
- It won’t cause problems for your registration.
Since the subject is the same, we can use the conjunction and to make a compound verb with the same subject.
But there’s more in common than the initial subject alone; there’s also the will not part, so that bit can also be can be factored out under conjunction reduction.
Conjunction reduction is perfectly normal, and usually reads better than not doing so, but you need to be careful that the remnants after reduction have enough parallelism that the reader will immediately understand to silently distribute the reduced part to both pieces.
Here your X and Y pieces are a bit unlike each other, so it may risk confusion. What I mean is that it’s a little odd because X is be counted while Y is cause problems. This makes the reader re-parse to make sure they’ve got it right. They might also be unclear whether the negation part distributes: does the not part apply to both pieces or just to the first one?
Other conjunctions are possible:
- It will not be counted as a typo or cause problems for your registration.
- It will neither be counted as a typo nor cause problems for your registration.
It is certainly possible to use won’t X and Y to mean won’t X and won’t Y, but it’s also clearer to repeat the won’t part as you suggest. That way people don’t have to figure out how much reduction you’ve applied here. One possibility is to skip applying any reduction at all and joins the two bits with a different word that better shows the implication you’re trying to make:
- It won’t be counted as a typo, so it won’t cause problems for your registration.
That’s a lot clearer.