Adjectival

Things that modify nouns (adjective, or adjectival equivalent).

It's apparently an alternative adjectival form, so this sentence should be fine.

adjectival syntax

adjectival noun

As we can have the adjectival forms bright, brighter, brightest, so we can have the adverbial forms brightly, brightlier, brightliest, but degree is alike inconceivable in the adjective ‘round,’ and the A. ‘here.’

Almost all of these names are adjectival in form, derived from some other personal or place-name, usually by the addition of the suffix -ius, -aeus, -eius, or -eus; […]

Within this line of reasoning, then, Tagalog is classified as a language in which adjectivals are essentially neutral between a nouny and a verby interpretation.