Yes, they speak freaky wacky Interlac, the Interstellar Language of the Future. Actually, DCU aliens in the present also know Interlac, but somehow "The Interstellar Language of the Present" doesn't have quite the same ring to it.
If you didn't already know Interlac, I'm sure you've had plenty of opportunity to ponder, peruse, and even decode it, while waiting for something to happen in the Lightning Saga (such as the death of Geo-Force).
Now, for convenience sake, Interlac is presented as a transliteration of English. But Interlac is different from English. Deeply, perversely different, as any attempt to translate it shows.
How do I know this? Grife, just listen to people in Legion stories talk! Almost every sprokking word balloon sounds something like this:
"Oh, how I despise Sun Boy for dooming us this way!"
"For displaying such weakness, we are imprisoning you here for all time lest you betray us again!"
Not even I talk that way. It's like reading a strict translation of Livy (in this particular case, his synopsis of the Peace Treaty from the Second Punic War).
You remember Alaktor, inventor of the transdimensional adult diaper-tard? I assume the "thing he's after" is a changing station, which would explain his walk. Anyway, try to picture yourself saying, "I'm getting near the thing I'm after!" Now picture that you're wearing that outfit when you say it.
Sometimes I think Interlac is kind of like Mohican or maybe Chippewa.
And sometimes it's like...
okay, I give up on this one. It sounds like when I tried to speak Hausa in high school and all I could ever spit out was stuff along the lines of "Your pigs are eating my yam field".
Anyway, don't blame the Legionnaires if they sound "funny" to you. English simply isn't well suited to translating the genius of Interlac.