More generally, what factors determine which phoneme a non-phonemic foreign sound gets rounded to in a specific language when there are multiple possibilities available? Is the choice always consistent within a language or even per speaker?
For example, I suspect that Hebrew roundings of French vowel sounds aren't always consistent: I've heard /y/ rounded to both /i/ (e.g. /brisel/ Bruxelles and for some speakers /ti/ tu) and /u/ (e.g. /fondu/ fondue and for other speakers /tu/ tu).