This extension constructs wikitext for a list with links to subpages and parses it to render the subpage listing. So, we can continue to render this with the legacy parser for now - there is no great loss in not having Parsoid-style HTML for the subpage links, especially given its sparse usage ( only enabled on cswiktionary and wikiversity besides labs and test wiki ).

I am removing this as a blocker.

I added back the parent task -- that epic isn't about read views necessarily - but about ensuring these extensions have native Parsoid handlers.