I’ll chip in. If you need demographics, I’m 24/M and graduate with my Masters on Saturday. My stutter is noticeably worse in any second language. I took Spanish in high school, and it was honestly the least-bad, but when I’d switch to Spanish I would block a looot more. In undergrad it was so much worse. I took Japanese, and speaking it was a disaster of monumental proportions. Thankfully the class didn’t focus on that too much. And now that I’m learning Czech independently, my mouth doesn’t like the consonant clusters. If I had to guess I’d say that speaking Czech correctly is even harder than Japanese, just due to Japanese having a lot more vowels generally, but it bothers me less in Czech because I’m not being graded on it, you know?