Council Van :
Transition altitude is not constant for the whole of Bulgaria and does vary from airfield to airfield,
Did not know. Thanks for the info. In many places the TL is uniform and really not relevant to the terrain in most areas in the country. Just take USA as example.
For not trusting the controller with terrain, you have nowadays to trust the system,i.e. follow the SIDs and the vectors and alt restrictions given by ATC on departure, and it is ATC responsibility to keep you clear from terrain.( ICAO PANS OPS) Under your own navigation it is your responsibility, but fortunately many ATC systems have today a terrain warning based on mode C/S returns that will warn the controller in case you are too low to penetrate certain areas.
Anyway in this case here, if we are to believe the AvHerald, the controller spotted the problem.
The decision by the crew to stop climb at 10.000 was probably taken during the stress of the event , and, when told, ATC intervened and added safety .
The " communicate " part did help here.
The whole interaction seemed to have worked quite well I would say.