As for licensing, I suspect a more thorny issue, an FAA IR 'swapped' for an EASA IR having met the requirements will be the route. The jury is still out on the requirements, but our work has been submitted and is under review.
So ... you're saying that for the IMCR holder the route will be
(1) get an FAA IR (because the hours already undertaken for the IMCR count, which they wouldn't in Europe)
(2) swap this for an EASA IR?