I looked at this last night. Good work with the sequencer, octave selection is something I was planning to do but didn't yet get to. I changed some things: the basic note selection needs to be +-12 semitones, and there shouldn't be rounding after the tune dial.
I also changed the filter to be 3 vcf3's in series with resonance on all of them. I'm still not sure if this is the right way but it sounded better to me and naturally cut the bass as reso went up (which seems to suggest this design is closer to how it should be) so I got to remove the high pass filters.
I'm not sold on the crossfader before the filter because of phase issues if you have it at anything except the extreme left or right.
The accent needs to get better for sure but it's doing stuff in the right ballpark at least: it shortens the FEG decay to minimum, and depending on the amount on the dial it will increase amplitude and FEG depth. Depending on the amount of resonance, accented steps will have a longer attack on the FEG as well. Needs fine tuning but first the FEG needs a rebuild, then we'll see where we're at with the accent (and filter in general).
I'll post the updated patch based on your v5 changes tonight.