Keller(?)/RAZNO Russian Piano

[Astraga]

Hello everyone. I just bought a Soviet piano from a reseller of old items in Italy and I have difficulties tracing its specific origin.
Outside it says it's a "Sonata" model by a certain Keller (or Heller, don't know which is correct) - in normal letters, not cyrillic - but inside the piano, on the top of the right side there is a plaque that says "RAZNO". Searching on internet gave me very little info but it brought me here so I though about asking. Also, with the piano there was an insurance paper that says it was taken away from URSS in the April of 1990.
Anyone can tell me where in the URSS and when it was made, more or less? The only piano catalog online that mentions this brand says that the RAZNO factory is in Ukraine and so I also wanted to be sure I didn't just buy a piano that has been contaminated in the Chernobyl area. Photos attached show the brands.
Thanks for the help!