I used flashrom on tinycore linux by PCEngines to flash apu4_v188.8.131.52.rom to my APU4C4 board.
These are the version numbers I get after updating the flash rom to v184.108.40.206:
PC Engines apu4
coreboot build 20190901
BIOS version v220.127.116.11
SeaBIOS (version rel-18.104.22.168-0-g393dc9c)
PC Engines apu2 setup v4.6.12
What I am wondering is that the setup menu says "apu2" setup v4.6.12.
Why would that identify as APU2 instead of APU4?