Hello Umberto,
I encountered the catering never stops bug, especially with the MJC Dash 8.
Since I was fiddling around reading the L:Variables to control doors with LINDA I think I found probably the bug which causes the never ending catering.
For the MJC Dash there comes a catering truck with catwalk and a normal van. The state then for the variable "FSDT_GSX_CATERING_STATE" stays then on 4 and never changes to 5.
If two trucks are arriving (with other aircraft) or two vans arrive (also with the MJC Dash), then I get the normal catering state 5.
If caterings ends then, after the vehicles have disappeared, with state 5, everything is ok and will be set to state 6. But if two different catering vehicles arrive, the state will never leave #4.
Hope that is the right direction ...