I have a 1929 Bosendorfer grand (one of the 'golden age' Bosendorfers) which I bought in 2004 after it had been fully restored - in Poland.
Particular skills were developed in Poland during the Warsaw Pact years when concert halls and conservatoires could no longer rely on technicians from Hamburg etc to maintain their Steinways and other top end pianos, and those skills have been retained in several specialist renovation companies. The dealer in Kent I bought it from specialised in period Bosendorfers, and always sent his acquisitions to the same Polish firm for restoration. Shortly after I'd bought mine a problem became apparent in the bridge/soundboard interface. So my dealer arranged for two guys from the Polish firm to drive all the way from Eastern Poland (can't remember exactly where, but I know it was near the border, so perhaps not far from your present neck of the woods) to pick up my piano here in Devon, take it back to Poland to replace the bridge, and bring it back again a few weeks later.
we got ours restored in Kielce - but that isn’t in eastern Poland