I really can’t say why consolidation hasn’t properly progressed in Central Europe.
Accurate statistics are quite poorly available for free (they might be found in companies’ investor presentations). UPM is, however, the market leader in the graphic papers market with a market share of less than 30%, and on the other hand, there are still dozens of small players.
Smaller companies rarely have the means to invest significantly in transitioning to other products (though some conversions have probably been made, for example, to packaging papers). With grit and luck, they will probably continue to struggle until the bitter end, and at the same time be a thorn in the side of the larger groups.