Barsoomian is public domain, unless it is the most recent movie version.
But here is one that I just notice: Parrot from Doctor Dolittle:
“Is the porridge hot yet?”
Oh, boy. How shall we do an interlinear gloss for that?
I’m going to guess ka-ka-oi-ee is a compound word meaning porridge and fee-fee means ‘now’ and reduplication means a tag question. Since reduplication indicates something you don’t know, then ka-ka would be “mystery” as in mystery-meat. So “mystery-food, now-now?”
And the dog speaks a constructed sign language.
And I’m going to guess that after page two the author lost interested in actually describing the fake languages. A pity.
But hey! It’s public domain. You are allowed to fully develop the language and sell it. Go forth and do so!