The previous implementation seemed to be a bit too greedy with the filenames that it selected to be built into the wrapper targets. There’s a bit more info in this thread: Bug? Filenames and underscores - #4 by reuk
It’s possible that the intended behaviour was to allow files with suffixes like Standalone and VST3 to only be built into the corresponding targets, but I don’t think this behaviour is documented, and the previous implementation looked like an accident, which is why it was removed.
If there’s a compelling use-case for this functionality, I’ll look at re-introducing it. In the meantime, I’d suggest using the runtime wrapperType technique that @PluginPenguin suggested instead.