HaikuPorts is hosted on github, so maybe some day when I get some time, I might be able to submit a pull request that fixes what the Haiku reorg broke. More than likely, it's the willy-nilly relocation of folders/libs that broke the plugin functionality in the first place. I believe they're also eliminating the launch script (which would enable them to set the proper env vars to allow the relocation to still work for all of Sigil's various pieces).
https://github.com/haikuports/haikup...app-text/sigil
All the pieces and modules necessary for plugin functionality to work have been listed as dependencies, so it would be quite silly not to just go ahead and make it work.