cywiki has wikitext of this form on lots of pages:
{{First word|{{#invoke:Wikidata|getImages|P242|FETCH_WIKIDATA}}|sep=]}}]] ..The inner {{#invoke .. }} generates a well-formed image link ([[..]]) .. and the {{First word|...|sep=]}} strips the trailing ]] and then the top-level puts that ]] back in. First word invokes a lua module to do regexp-match based on the sep and returns a matching string. Of course, Parsoid doesn't support this because it doesn't support concatenation of two strings to be treated as a link. I don't understand why they have this bizarre usage (presumably at some point they appended additional top-level image options?). But, in any case, for their current usage, it looks like they can simply get rid of First word wrapping around the getImages wikidata call and be done.
This insource search shows ~18K pages affected. As far as I can tell, they are all automatically-generated articles written by [[User:BOT-Twm Crys]] based on town/location information in wikidata.
Replacing:
{{First word|{{#invoke:Wikidata|getImages|P242|FETCH_WIKIDATA}}|sep=]}}]] ..with just
{{#invoke:Wikidata|getImages|P242|FETCH_WIKIDATA}}ought to fix the parsoid compatibility issues.