In the 1.2.5 and maybe 1.3,2 versions of the Fossils and Archaeology mod, due to the way it was created, it is technically two mods (the base mod and a addon) and as such the widget labels the blocks as from AddonTimeMachine and not FOSSIL / ARCHEOLOGY, as would be correct. I don't know if this can be fixed, due to the way the Fossils and Archaeology mod is made, but if you need the mod as it is hard to come by, I can give it to you.

Block Helper only fetches the mod names from the mcmod.info and BaseMod's methods.
I don't plan on hardcoding too many fixes, sadly.
It is also worth noting that Block Helper can not differentiate between mods if no appropriate class extension is being made. Thus, if your mod adds a block that directly instantiates, e.g. BlockWool, then Block Helper will not be able to differentiate your block from Vanilla ones.
Other approaches are sadly difficult (also performance-wise) or even impossible to implement.

Thank you anyways for reporting!