Aren't these marks only used for the word in the article you're already on? When would you need this for a new search?

not sure what your concern is exactly @jonnyl2, multiple dictionaries have different entries, for example Collins has an entry for "stratum" that has the noun "stratal" which has it's own separate entry in the OED. A man is free to search multiple dicts.

Also, many OED headwords have stress marks as well, many a time have I also needed to search the headword again.

I will now take this time to shamelessly plug the oed_prettifier mainly because instead of focusing your energy on questioning whether stress marks should remain or go, you could be helping make a better OED for all. I need people to report issues they encounter, I can't do it alone.
Tangentially, my friend sent me a screenshot the other day in which he asked Gemini what the oed_prettifier was... Gemini said, and I quote here: "It's a niche tool for bibliophiles" ouch.

It's alright, I've just never encountered them in years of KOReader dictionary use (but then again, I don't use the OED or other fancy dictionaries -- maybe I'm not bibliophile enough). But I'll take a look at your project, since you asked nicely.

They occur plenty in my paper dictionaries in any case.

seven days... 🎉