Suppose, if i replace a midfield player at position M-RC-1 with an attacker and switch him to A-RC-0, will he be treated as an attacker or a midfielder…

till now i had thought he would be an attacker, but check this match report, it says something else.
Check player Marco Della Picca. he is an attacker, but he replaced a midfielder as an attacker, but it shows he is a midfielder.

i am more worried about him losing 3 skill points on each skills

I wouldn’t worry about losing points, looks like a match report position display issue rather than a match positioning problem.