The term you are looking for may be "highly inflected".
Side note: IMHO, you are exaggerating the ability of Polish to form long compounds. Dissecting the "Bezbarwne zielone idee wściekle śpią" example from https://arxiv.org/pdf/1810.10222.pdf#page=3 reveals no words longer than 4 morphemes:
bez-BARW-n-e ZIEL-on-e IDE-e WŚCIEK-l-e ŚP-ią, where I put word roots in uppercase and bound morphemes in lowercase.
The longest sequences of morphemes (for a loose definition of morpheme) I can think of are conditional mood of verbs with double prefixes like po-wy-CHODZI-ł-y-by-ście. However, the sequences of bound morphemes in those forms, which may look complex to you, form a finite-state language that admits just a few sequences.
Side note: IMHO, you are exaggerating the ability of Polish to form long compounds. Dissecting the "Bezbarwne zielone idee wściekle śpią" example from https://arxiv.org/pdf/1810.10222.pdf#page=3 reveals no words longer than 4 morphemes:
bez-BARW-n-e ZIEL-on-e IDE-e WŚCIEK-l-e ŚP-ią, where I put word roots in uppercase and bound morphemes in lowercase.
The longest sequences of morphemes (for a loose definition of morpheme) I can think of are conditional mood of verbs with double prefixes like po-wy-CHODZI-ł-y-by-ście. However, the sequences of bound morphemes in those forms, which may look complex to you, form a finite-state language that admits just a few sequences.