On grammatical class:

no'au
Introduces a bridi relative clause, with the scope of {xoi} and the semantics of {noi}
xoi
Right-scoping adverbial clause: encloses a bridi and turns it into an adverbial term; the antecedent (ke'a) of the enclosed bridi stands for the outer bridi {lo su'u no'a ku} (the bridi in which this xoi term appears), including all the other adverbial terms (tags...) within this bridi located on the right of this xoi term (rightward scope).

In notes:

gi'ei
afterthought abstraction wrapper
i'au
reset bridi-level to zero
adverbi
x1 is an adverbial adjunct (adverb or adverbial clause) meaning x2 in language x3
faunli
x1 (nu) happens together with x2 (nu); x1 happens while x2 (one sense)