In fact, question from the title.
Are there any traditions, customs about stressed syllables of brands?
The problem is - many of brands contained fictional words, which, of course, have not been used ever before.
Both Companies and individual people (I'm looking at you, Stephen Colbert) do this all the time. You can decide how you want your name pronounced, you just have to convince everyone else to pronounce it the same way. That might be difficult for words and names you've made up, particularly if they don't follow normal phonetic rules.
This reminds me of the oil and gas company Schlumberger. It's a French company, and their name is pronounced Shlum-ber-zhay, but as they have a pretty large presence in America many people here mistakenly pronounce it Shlum-ber-ger before being corrected. My cousin worked there and told me that interviewees who mispronounced the name had a serious strike against them.
It depends on what you mean by "determine."
Can companies suggest a pronunciation of their brand name? Yes.
Can companies enforce a pronunciation of their brand name? No, except among their own employees.
You will sometimes see companies include notes on pronunciation in press releases and such, and most journalists will follow that lead as a matter of good practice. (For example: soccer team "D.C. United" used to include at the bottom of every press release a request that journalists not refer to them as "the United.")
But ultimately, this is only a suggestion. If you open a restaurant and put up a sign that says "A Taste of Paris," people are probably going to say "Pah-riss" even if your waiters say "Welcome to A Taste of Pa-ree."
Relexification is commonly used for marketing a company or product to English speaking consumers