It does make sense since the M2 is an American weapon, and it would improve both Mobile Assault and Royal Engineers.
I like it.
Tbh I think both those abilities are valuable enough to be slots in their own right.
The OKW Assault Package is different because there's not much of a performance boost over the stock upgrade path.
Flamers, however, are a major upgrade for Sappers.
I'd rather see repair aura and some sort of offmap type ability, as opposed to a unit. Honestly, I liked the idea of smoke raid operation as long as you have some way to repair m10 hordes. Fits really well thematically and it'd be useful for a faction that tends to struggle with assaults.
It's already got smoke from the mortar. It was getting a bit smoke overkill.
Crew repair is much more important given the commander's tendency towards lots of <100 FU vehicles.