UN54 is an old East German film. It's currently sold as Ultrafine Xtreme ASA 100. I've heard it called DDR100 for its East German roots. I had some Rodinal...and somebody mentioned this "old school film" mating up nicely with Rodinal, allegedly the oldest developer still being sold. So heck, I bought a 100' roll and a Alden 74 winder....and here are the results. Old, meet old.
Lots of Rodinal information out there. Development times are all over the map, so I used the published instructions (Google "Rodinal leaflet"). While this film is not listed, there are a number of ASA 100 films on the chart.