Cautious is okay. Mine is TIG'd and new SUMOs, no issues. Had a heck of a time with it but once I got it sorted it worked out.
I just can't figure how your's cracked like that. weird.
Hire a guy with a TIG and fix it. If you clean it up, spot weld it, then go.
So long as the idler hole alignment is good, and the case is correctly positioned
no reason to think it won’t be fine. You could TIG a brace right into it.
Rebuild kit, maybe some new SUMO gears.