A "source" told me today the fix is to reverse the calipers so n/s to o/s but upside down. Then they only squeal going in reverse. Is that true? It seems a very MMC solution

Yes it is true,but there is a kit

Spanner and bottle of Dot 4

And maybe new decals on the calipers? Or maybe you need slightly different pipes

Dont know if it's due to the kit but two times my brake pedal went to the bottom just after starting up the engine

I think I would be calling the dealer ASAP.

If the calipers are turned upside down, and the bleed nipples are then at the bottom, bleeding becomes harder.

But if the pedal drops on starting the engine, it also suggests the servo is causing that effect. Maybe some air still in the system.

Whatever is going on, it needs looking at.

But I wonder if the kit adapts the calliper so that the bleed nipple is on the top?

I have found it occurs only when the wheel is turned at the maximum at slow speed ( 1gear).
Same max left or max right.it was not there before the correction for the squeal.
Tomorrow the garage will check with a plus four with the modification. If i release the wheel
A little the brakes come back.

It could be I guess a trapped pipe on full lock.