Some special (HUN, DE) characters cause empty display in Receiver Radio app

Receiver Radio app fails to display song metadata in case of certain Hungarian (e.g., é) or German characters (e.g., ä). In these cases empty metadata is shown in the player. Note that it works for some Hungarian accents e.g. "á". 

First hint I found: https://stackoverflow.com/questions/31044773/liquidsoap-tag-encoding