To be honest I don't now how they arranged to test their TV sets. I think they could have imported some modulators and test pattern gernerators from Germany where TV was introduced earlier.
I have also no doupt that the engineers had the ability to build their own equippement based on the knowledge and experiences of other countries.
All in all is to say that the te quality standards where quit high here in Austria. Transformers, switches and rotating capacitors are still ok until today in 99% even though a device was stored in a damp basement for ages
