https://www.cbr.com/marvel-rom-spaceknight-dire-wraiths-hasbro-trademark-lawsuit/

However that article speculate why Marvel withdrew their attempt to challenge the rights claim of IDW but doesn't know why.

Well there is a commercial for the ROM toy where the narrator mentions that ROM's enemy is the DIRE WRAITHS. Also I think the old toy package mentions the Dire Wraiths also.

Marvel did design the Wraiths in terms of appearance and powers, but IDW has their own unique look for them and same or similar powers.

But I would guess that since the old commercial mentions the Wraiths by name that they are in some way linked to the ROM trademark, so if IDW has ROM then they should get the Wraiths as well.

The commercial that mentions the Wraiths is here:
https://flashbak.com/outer-space-toy-store-rom-space-knight-parker-bros-1979-57592/