Recently, a set of new transliteration rules are added to handle case-transforms for a few languages (Greek, Lithuanian, Turkish), but Mozilla/Firefox has more sophisticated rules for Greek and Irish.
I wonder whether it's worth taking a look.
See their codes at
FYI: For ICU 58, I will try to implement at least the Greek uppercasing in the low-level ICU case mapping functions. There are several related ICU tickets.
There are some test cases for CSS3 text-transform for Greek tailoring
FireFox is mostly compliant, while others including Chorme/Safari are not. I guess Chrome/Safari depends on CLDR's Greek uppercase transform data (tonos is dropped, but dialytika is also dropped).
Chrome uses CLDR's el-Upper. I'm not sure if Safari does (it may not. It did not in the past).
Thanks, Markus, for your plan to add Greek uppercasing in the low-level API.
Well, Safari still fails. You must have mistaken Opera for Safari. (Opera uses the same engine as Chrome - Blink - so that it should behave identically).
CLDR 34 BRS closing item, move all upcoming → UNSCH