4.15 is at the Amiga Hardware Database: here.
Thanks for the link! Unfortunately, they all include v4.14 of the library. From what I can gather, 4.15 might have been a beta library with a few small fixes before the 4.16 series was released.
What I've discovered after some more recent tinkering with the Delfina Lite (2 cards here, revisions 1.1 and 1.2) is that 4.14 (fake crash requester and all) is absolutely the most reliable version I've tested for MP3 playback, especially regarding internet streaming. This includes the patched libraries. You'll still get crashes with higher bitrate streams (overclocked or not), however at 96k it will run for days - but only with the 4.14 library. Doesn't matter what Amiga (Z2, Z3, etc) or accelerator combination.
Still wouldn't mind a copy of the 4.15 lib, if anyone's got it. :-)