I am thinking about a houserule which gives the players access to different languages via lore.
You start with one language, every point in lore learns you another one.
In my vision, i would make two main languages, oldspeak and alderish.
Alderish is the language of the alderlanders, oldspeak the common tongue of dwarfs, elfs, elvenkind, orcs and ailanders.
As additional minor languages, i would make:
Belifar (goblins and halflings)
Dwarvish (old language, mostly used by stonesingers)
Elfish (Old elvish, used by runemages)
Maha (secret, raven and clay druids)
Wolfish (called howling, wolfskin language)
Dark tongue (demons and blood mages)
and languages for lizardmen, whiners and ogers.
What do you think.