I'm describing the issue after my "pretty buggy" comment (no harm intended, sorry).
I'll record a video of what I mean and send it to you asap.

One thing I noticed is that the interpolate kerning and the autokern from features is pretty buggy. It would be great if I could set it to "copy" the same kerning from another master. Say I have regular and italic with the exact same setup but slanted and want exactly the same kerning. Rig...

I have done this and it's possible. I've set zero models for the letters that were connected. Sometimes Kern On insisted on trying to kern them, especially init, fina versions of the same glyphs. It took me a while and some headache but in the end it all worked out.

I have a typeface with masters that are exactly the same metrics/kerning with just minor letter tweaks. Can I set Kern on up in a way that copies the kerning automatically when generated? I know I could just copy paste it afterwards but it's not an optimal workflow.

Perfect, that makes sense, even though I need to include figures in my feature – probably need to investigate how to make that "non-susbstitution" in a way that's not going to cause further issues

Hey Tim, it seems like the new versions is making Glyphs hang in the rainbow of death :)
I am opening a file that already had a setup using the previous version of Kern On.

On my latest trial, the results were much better than last time, indeed.

One thing that is bugging me about the generated kerning groups is glyphs with diacritics receiving their individual kerning groups. I haven't yet done something like that in previous fonts ever so I'd think that KO_o = KO_oacute always - component glyphs should probably inherit the kerning groups o...