Frog in the throat!
Frog
You are allowing yourself to be dragged into a downward spiral going nowhere, some thrive on it. You have until now kept above bickering, keep it that way. Human Factors, remember..........!
From the recent interlude, perhaps, your able now to agree that there is no such thing for a fully qualified UK Flight Instructor to have an IR Instructor rating as a seperate attachment. Only an Instructor Rating with the 'no applied Instrument training endorsement removed exists, at least within the UK.
For the purposes of the USA I presume an Instructor with the UK Flight Instructor 'no applied .........' endorsement removed, having validated a pilots logbook, satisfies their requirement. The holder of an IMCr will by holding the IMC rating be able to demonstrate that they meet the requirement of 15 hours dual instrument training.
I can quite see that it will not be so simple for those outside of the UK to demonstrate the same without logbook endorsements, which may have lead you to your believe.