Re: FAA IR Conversion to JAA Multi IR in UK
I've seen no application form asking if your IR was done in a specific country. However, someone could obviously see where you took the test, and which examiner did it, by inspecting the log book.
I was familiar with a student who trained at my UK school for a CPL to add to their Spanish won IR. The general consensus among the instructor and the 170A instructor for the CPL was that their IR skills were appalling to the extent that they were touch and go for even the instrument section of the UK CPL. As with the UK, select your school very carefully.