It's unclear where the range_close should go for:

\indextext{overloading!argument lists|(}

Should that page range include the new [over.match.class.deduct] sub-clause, which is part of [over.match.funcs]?

And should [dcl.type.auto.deduct] and [dcl.type.class.deduct] be included in the range for [dcl.spec] started with \indextext{specifier|(} ?

I've fixed most of these, there are a couple more in pull request #1328 where I'm unsure if I moved them to the right place.

I think it makes more sense for the "specifier" index item to include up to the end of [dcl.type.class.deduct] than to end before [dcl.type.auto.deduct]. Likewise, "overloading!argument lists" should probably extend to include [over.match.class.deduct], since it does (indirectly) specify how to form the argument list for such an overload resolution.

Done.