Maybe not helpful, but I go with squeegying prints on way out of wash (NOT with same squeegy used on darkroom splashback for evaluation!) using the thick acrylic dividers from the washer.

Prints then go face up onto mesh drying screens, and curl like hell while drying, finally settling a little.

Finally, I crank up the secret weapon - an old Kodak drum glazer. The drum itself has a coupla scratches and could never work as a glazer again, but I set the thing going nice and slowly at a moderate temperature, and once it's warmed up I feed prints in. They go in on the belt face down. Care needs to be paid or you could get folded corners. Prints come out nice and flat once cooled again.

In my experience super curly prints that never flatten have almost certainly spent far too long wet, in which case you are washing to excess or you left them soaking overnight or something. The only evidence I've ever seen for Eastern European papers being less flattenable is the old Forte RC's - which were simply on a thinner base and had a much shorter wet time than Ilford's much heavier RC MGIV. Less mucking about and better washing fixed this no problem. I've yet to meet an FB that won't dry properly once you've bothered to find out what it likes and what it doesn't. General rider: any print will curl a little due to humidity at times. Restricting this may not be a good idea long term for the structure of the paper as a whole - note that archival mounting techniques stipulate essentially hanging the print in the mat from one edge...