The ".imgX"-files were hidden in a separate folder. JaVaWa did not detect or react on those maps.
Of course, I can try to remove everything that can possibly do any harm and keep only the four v3 files and the Gotalandv4 including the SQL-folder in Garmin folder. Doubt it will change anything.
I installed all four v3 maps and the Gotalandv4.img plus the SQL folder on a brand new SD card.
The Oregon did not see the v3 maps. Only the v4 map.
JaVaWa result changed. The earlier indication of "Read only" did not reappear.