After yesterday's cleaning, I was able to run engines on the full layout!
And running on the main tracks:
During this run, I realized there might be an issue with a double slip switch A4. Also, the BB 15000 was not liking the rail gap by the switch C2. While I've tested all sections occupancy and retrosignalisation, I probably have to test all switches going in all directions. This is for the next session ...