I work languages in the following way:
1) There is no "common"
2) I have regional languages that are known by particular countries (usually 2 or 3, sometimes including humanoid tongues, sometimes not).
3) If you have the same "language" as another speaker, you can understand each other just fine.
4) If you speak a language in that region (one of the couple languages known by that country), but its not an exact match, you make an Int roll/check on a d20, and the closer to 1 you get, the more information is able to be shared/understood. If you roll above your Int score, you aren't able to understand what they are saying. There may be penalties or bonuses (situational) for what is happening - in combat: likely penalties, over dinner or specifically speaking slowly: then likely bonuses.
When you travel outside of your region, then hopefully someone in the group studied a language out there, or you can hire an interpreter. I have also removed spells like Tongues and Comprehend Languages (or severely limited them), to make communication more challenging.
1) There is no "common"
2) I have regional languages that are known by particular countries (usually 2 or 3, sometimes including humanoid tongues, sometimes not).
3) If you have the same "language" as another speaker, you can understand each other just fine.
4) If you speak a language in that region (one of the couple languages known by that country), but its not an exact match, you make an Int roll/check on a d20, and the closer to 1 you get, the more information is able to be shared/understood. If you roll above your Int score, you aren't able to understand what they are saying. There may be penalties or bonuses (situational) for what is happening - in combat: likely penalties, over dinner or specifically speaking slowly: then likely bonuses.
When you travel outside of your region, then hopefully someone in the group studied a language out there, or you can hire an interpreter. I have also removed spells like Tongues and Comprehend Languages (or severely limited them), to make communication more challenging.