I keep seeing people ask about this periodically, It isn't easy to find on google, I got it from a reddit link, But someone made a way to get FSN/RN working in English on vita on this forum!
https://forums.nrvnqsr.com/showthread.php/8229?p=3111507&viewfull=1#post3111507
https://forums.nrvnqsr.com/showthread.php/8229?p=3111507&viewfull=1#post3111507