I think "even nicer" is correct english, you just needed to add an "r"
I didn't meant even nicer.
There is a polish word construction using word "nawet" (even) and an adjective. Adding "even" before a word indicates agreement with the adjective (like saying "nice"), but so-so agreement, when you want to avoid direct expression or you're amazed that something is good, like when commenting some new music album when all previous from it's composer where piece of crap.
Polish a bit complicated Razz