Welcome to the Vintage forum. You assessment of ETA 2878 is probably correct:
bidfun-db Archiv: Uhrwerke: ETA 2878
The movement was widespread and not just used in your country. Helvetia may have got a specialist to make day-of-the-week wheels in Romanian or it is even possible that ETA provided them with the movement in that language. But it doesn't indicate that the entire movement was only used in that locality.
The "0004.50" is probably the watch reference number (a sort of model code).
Hartmut Richter
bidfun-db Archiv: Uhrwerke: ETA 2878
The movement was widespread and not just used in your country. Helvetia may have got a specialist to make day-of-the-week wheels in Romanian or it is even possible that ETA provided them with the movement in that language. But it doesn't indicate that the entire movement was only used in that locality.
The "0004.50" is probably the watch reference number (a sort of model code).
Hartmut Richter