"Oh, this is the wrong bridge."
Translation:Oho, tämä on väärä silta.
Both of your example sentences seem to me to contain adjectives and not adverbs. In both "wrong" is an adjective qualifying the noun "answer".
"That is the wrong answer" "wrong" as an attributive adjective.
"That answer is wrong" "wrong" as a predicative adjective.
Does Finnish define adjectives differently to English?
Oh, you're right. I read it like this in the Duolingo tips and I'm pretty sure I saw some example sentences with 'is wrong'. I looked it up and this page suggests the adverb can be used with 'olla' (to be) specifically when it means 'incorrect', even though English would use the adjective in those cases: https://en.wiktionary.org/wiki/v%C3%A4%C3%A4rin