As Roland says we try to keep up to date with JUCE but as we release Waveform with the develop branch of tracktion_engine, we have to be a bit careful and that sometimes means being slightly off the tip.
The safest thing to do is just use the same commit as the tracktion_engine/modules/juce Git submodule is at (or the submodule directly) as that’s what the CI builds and all the tests are run against.
Regarding Discord, that’s a good place for general discussion and I try to dip in regularly but please bear in mind I can’t get notifications for when something is posted there (I think due to the size of the Discord) so responses won’t be immediate.