Thanks for doing this.  I hope it encourages more participation.

The capabilities of a triager mostly look good except for "closing PRs and issues".  This is a superpower that has traditionally been reserved for more senior developers because it grants the ability to shut-down the work of another aspiring contributor.  Marking someone else's suggestion as rejected is the most perilous and least fun aspect of core development.  Submitters tend to expect their idea won't be rejected without a good deal of thought and expert consideration.   Our bar for becoming a triager is somewhat low, so I don't think it makes sense to give the authority to reject a PR or close an issue.