Thank you so much for your kind words
I've done more reading last night and it seems that if they will be located the neuter will be more or less like a spay and that calmed my mind, just like you said.
The vet even told that in some cases if they can not find the testicles because they are so underdeveloped they offer to do a blood test first to check testosteron levels prior to surgery, to be sure they are definitely there and working.