Inflectional affixes ( prefixes or suffixes) don't change the part of speech, but refine it by changing the number, person, tense, etc. Your examples are derivational suffixes. Their specific purpose is to change the part of speech. -ness and -ment change verbs into nouns -ish changes a verb into an adjective

I don't know German, but Google Translate is showing me: He was a kind man, full of kindness = Er war ein freundlicher Mann, voller Freundlichkeit. This shirt isn't a true blue, but at least it's bluish = Dieses Shirt ist kein echtes Blau, aber zumindest ist es bläulich. So I think there must be similarities in German.