After redumping a few A2600 carts, I wasn't able to find their hashes into DoM (for example Space Invaders (P), with crc32 71627b6d).
A few researches later, I figured out that these values were already known and confirmed, but just not present in the db.
PAL region in particular seems to have many missing titles.
If someone is ready to work on that, it seems that MAME files contain a solid list of hashes which could be used to compare with DoM :
https://github.com/Klozz/xMAME/blob/mas ... /a2600.hsi