We thought we were better to let that issue aside for a while and Louis-Marie examined what he could do. Finally, he felt confident enough in his soldering skills (he's an electronic guy after all) to move the guard rails. We were a little bit afraid of destroying the turnout, but after a few minutes and with the help of custom jigs, the promptly corrected.
I'm now happy to report the 24"/20" radii curved turnout can now handle big power like M630C and, indeed GMD1. Styrene ties have been glued and soon a nice coat of camouflage brown will bring it to life.