Faeshu: broken English (because he was from the past, i.e. language drift); I was less proficient with English back then, too.
Mirrou: normal speech (because he had some of the best education in Thera), some mild interjections and cat emotes (no licking balls, though).
Barath: stereotypical scottish accent (grew with dwarves).
Kazzru: classic "felar speech" with lots of purrs, hisses and cat emotes (generally was a very unstable, chaotic, emotional character), always in third person because where he was from it was customary for lower-class citizens to never say "I" or "me".
Dhaiwr: normal speech, because he was initially meant to go herald storyteller.
Aronar: Spock Speak, because felar supremacist. He was simply better than any non-felar, at anything!
Kowelu: storytelling means good language practice, so normal speech with preference towards elaborate, flowery phrases.
I've had some more but I forget the names. I know I experimented with multiple "r" or multiple "s" and found it annoying to keep up.
These days I just don't bother garbling my character's speech anymore. There's emote and esay, and "genius" 17 int is enough to speak common fluently, if your character cares to do so, and I *will* find an excuse to want to speak properly.
Or just play a human.