Created attachment 410022 [details, diff] hiawatha-9.14-r1.ebuild.diff I don't know why the ssl and rproxy USE flags were declared broken in the ebuild, but I tested them and they do work fine (see the attached diff), so I think they should be added again.
By "broken", the ebuild author probably meant "changing flag value doesn't work". With your modified ebuild, does building with USE=-ssl work, and is ssl really disabled even if mbedtls is installed on the system? If yes, we can re-add the flags.
Created attachment 410554 [details] emerge.log Yes, as you can see in the attachment the USE flag works as expected.
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=6726730f1297aaad5ec7d98cde271c9c5d491a94