Rear admiral Chiraneau's ability reads: "While you perform an attack, if you are reinforced, and the defender is in the (Full front arc) og (Full rear arc) matching your reinforce token, you may change 1 (focus) result to a (crit) result."

Reinforce only works against ships fully inside the reinforces section. And since RAC's ability references reinforce, it's easy to assume that it applies under the same conditions. But a ship that is flanking (ie. in both the front and the rear) is still in the front or rear arc, even if reinforce never works.

Not really a question, but a rules interaction to be aware of as the decimator gets more popular.

I've fallen foul of this a few times and only recently learnt of my mistake! Makes RAC a bit better imo.

Yeah it’s easy to get caught up in the limitations of the reinforce token and assume that Rac’s ability behaves the same way