It’s not easy to determine whether Kid Vengeance actually qualifies as a Spaghetti Western …
• No, there wasn’t any Italian involvement production-wise: IMDb, German and Italian Wikipedia, TCM, BFI.
• Yes, there was: SWDb, English Wikipedia, Kevin Grant (p. 467).
The fact that the film doesn’t have an entry in ANICA’s Archive of Italian Cinema might be a crucial indicator. But the information on ANICA’s website is of course anything but reliable.