You didn't mention it but /ɹ/ for /ɾ/ and /r/ really bothers me, even though my teacher said that many Spanish speakers can't trill their /r/'s. I'm pretty sure they don't use /ɹ/ as a substitute.
They do use [ɹ]. My brother is one of them. Apparently, he has a particular ligament length under his tongue that doesn't allow him to trill his /r/, but he refuses to undergo the small operation.
I've always mocked him for being a native Spanish speaker and yet he doesn't pronounce /r/ as he should.
Aw, man, you're mean.
I've always felt ashamed for never being able to pronounce my /r/'s because I'm a native Russian speaker. I always hesitate to say words that start with /r/ because they make my accent ever so noticeable. I often resort to using /ɹ/ as a surrogate /r/, but... it doesn't sound right.
Do you think that /l/ for /r/ is a good replacement?
The ligament under the tongue is only removed when you're very small, and only when recommended by doctors.