Other Mando'a dialects
Concordian (appeared in The Clone Wars)
This dialect of Mando'a was based on a fan's interpretation of and extrapolations from the Republic Commando lyrics; this is one of the oldest extant fan expansions of Mando'a: https://www.swgemu.com/archive/scrapbookv51/data/20070127004230/index.html
Concord Dawn (appeared in some Republic Commando books)
And the Concord Dawn dialect has "F", "X", "Z" and a couple of other letters Mando'a doesn't use.
So those guys are either named from a different culture, a different dialect, or (third option) their names have been corrupted by Basic over time.
Imagine that in four thousand years, Kal Skirata might be spelled "Kal Zkirada."
So, Xaga might have been "Shaga" (incorporating that "sh" sound the Mando like) and Zuka could've been Suka.
Ryan Kaufman (DHC Author & Former LucasArts Content Supervisor), forum post, September 14, 2005, https://boards.theforce.net/threads/mandoa-class-mandalorian-language.21531491/page-7#post-21561289
TheDave said: "Is the language spoken on Concord Dawn a dialect of Mando'a or is it completely different? Also, What form of Mando'a exactly are we speaking of in this thread (as in, which planet is this mando'a from, if mando'a is spoken in different planets like I'm assuming)?"
Mando'a is separate - it's an ancient language taken from the gray-skinned Mandalorians. Mando'ade have a lot of Concord Dawn blood in them (a factoid that I got added to continuity for reasons that will become clear shortly.) That's all canon/continuity.
Extrapolating here: Concord Dawn would probably be a different language but one that has picked up Mando'a words from long association. A lot of Mando'ade come from Concord Dawn and end up back there. The flow is from Mando'a to CDish.
EDIT: I should have added - there might be accent variations, but Mando'a has remained remarkably unchanged and unaffected by other languages, because the Mandos just switch to basic and Huttese when they need to. And it's consistent from place to place, because it's an intergral part of the culture - almost sacred, although that's not the right word.
Karen Traviss, forum post, September 14, 2005, https://boards.theforce.net/threads/mandoa-class-mandalorian-language.21531491/page-7#post-21563179