"Old Hungarian (for ligatures)" need "ZWNJ" key.
The Old Hungarian font of Google's noto fonts projects use discrete ligatures, which make in some cases spelling problems with ligatures "x", "q" and "w", because of that discrete ligatures are have automatic process. For example Hungarian word "keksz" appear as "kex" (of course it must be understood written with Old Hungarian letters). It could be broken with zwnj (zero width non joiner) key only.