Languages in Kelvernia

I've been going back and forth about how to use languages in Kelvernia. One thing I mislike in games (and never use) is the idea of alignment languages. What I do like is the idea that not all humans speak some "Common Tongue" fluently, or that this lingua franca is as detailed as a normal, "native" language. I also like the idea of using languages as a challenge and to add flavor to the game. 

What I don't want to do is make it so players are either: 

1. stuck with all playing characters from the same background or nation, or 
2. unable to communicate with one another in-game

Neither of those sound like they would be much fun over the long haul. 

So here's what I'm thinking of using, house rules-wise.

• All PCs speak their native language AND the Common Tongue.
• As per the LL rules, characters with an INT of 9+ are assumed to be literate.
• "Common" is a pidgin/trade speech which can convey most straightforward ideas and concepts, but is not a great choice for composing epic poetry or making flowery speeches.
• Many NPCs will not know Common.
• Demi-humans gain no automatic bonus languages. (i.e. Kobold for dwarfs, etc.)
• As per rules, High INT gets additional starting languages.
• It is possible for anyone to learn additional languages after start of play, but it takes weeks of study, practice with a fluent speaker, and/or immersion in the language's culture.
• Once per week, the character trying to learn a new language attempts an INT check, three total successes means the character has gained basic fluency. 
• A character cannot learn more languages than a total of half their INT score (rounded up).

In Kelvernia, the people of Cramond, Tyros, Jerimet, and Sulat all speak "New Imperial", a modern form of the old Sulati language. The other nations each have their own languages. Elves and dwarves have the own racial languages. There are also dead languages in Kelvernia also possible to learn.

Since all PCs know the Common tongue, no one is required to go out of their way to learn more languages. It might make some challenges easier if you have someone in the party who can speak Glaw, but no one is pigeonholing a character into it.

("Let's see... How would one decline 'Guisarme' in Ogre?")