Im not best placed to answer this, other forum members will know more, but no ones answered yet, so i'll say what i think.
So. Never heard that term (although i kinda guessed what it meant) before but according to stackoverflow youve just set it up to build using maven rather than say gradle (can you gradlize as well?)
Anyway. Does mavenizing make any changes to the soapui project.xml? I don't think so (but thats a guess on my part). Logically, if it doesnt make changes to the project.xml file it shouldnt make any difference when it gets executed.
I suspect your groovy script errors have nothing to do with automating the build process with maven, although this is a guess on my part, but to confirm, what happens when you execute the project manually (without adding to CI to execute)? Do you still get errors? That'll at least point towards the cause.
If you get errors running the project manually it'll be problems with your groovy most likely. Can you publish your groovy so we can see it?
if this helped answer the post, could you please mark it as 'solved'? Also if you consider whether the title of your post is relevant? Perhaps if the post is solved, it might make sense to update the Subject header field of the post to something more descriptive? This will help people when searching for problems. Ta