I also speak or have spoken those 4 languages as well, but my experiences are a little different. English is my first language and I am by far the most comfortable/confident in English and have learned strategies to help my stutter in English. I probably stutter 20-30% of the time in English and it's mostly minor stutters (gets worse if I am tired/nervous etc.) I lived in Italy for a year when I was 18, and while I got comfortable and quite fluent in Italian, I still stuttered more in Italian than English, although it got slightly better, the more comfortable I got at speaking the language. I also had the opportunity to live in Mexico for half a year, and studied Spanish in University. I am not fluent in Spanish, but I still had the same experience that when I got more comfortable conversationally with my Spanish speaking skills, my stutter got slightly better. When I travel in Spanish speaking countries now, I stutter WAY more in Spanish, but I think it is a comfort thing with not being fluent/trying to focus on the language so my stuttering strategies go out the window. I did French Immersion in high school, and was never fluent in French so again, different experience as you, but same to the other languages in that I stuttered more in French than English. So for me, I think it boils down to comfort with speaking the language is what makes my stutter better or worse, but even at my peak Italian fluency, I still stuttered more in Italian than English.