Two things, one restart.

The 10-second home-refresh ticker read last_home, which was never initialised:
my init patch targeted the pre-merge line and the merged code had renamed it
(last_labels joined the chain), so the replace silently no-opped — I had
asserted every replacement in that patch EXCEPT this one. The driver died at
its first tick, 10 s after start, while the surface kept showing the labels
the startup had already written: a dead translator behind a live-looking
display. Fixed, and verified past the tick this time.

And the stuck "0" PLN saw on row 3: arrangement 4's numeric value is drawn by
the FIRMWARE from its own internal control value, which never moves for a
relative encoder — the driver owns those values now. So the driver echoes each
integrated value back to the device on the encoder's own CC (plain DAW-style
feedback). --no-echo exists in case the echo ever fights the RGB paint; the
2 s paint reassert heals any skirmish regardless.

Next display experiment, deliberately not built blind: arrangement 1
(host-supplied TEXT value) on per-control targets, which would let
probability-style constructs (sometimesBy / someCyclesBy / midiOn ranges)
read as percentages instead of 0-127.