Support for more languages?

It may be worth joining efforts on the same plugin rather than scattering through various projects.
The .ctags version of symbols-tree-nav has been patched several times, maybe you could take it to update the one of structure-view to better support languages (and/or support more)?

symbols-tree-view, as well as symbols-tree-nav, uses an external binary to parse the files, I think the support for several languages is only due to this binary even if the current version is broken for several languages in symbols-tree-view. For instance there's no regex for python in the .ctags files of symbols-tree-view (nor symbols-tree-nav), yet python is supported. I don't understand completely how you parse files (looks like everything is done in javascript?), but maybe an external binary would allow a support for more languages?

Start by reading the JavaScript parsing logic and comparing the .ctags configuration with the versions used by symbols-tree-view and symbols-tree-nav. Determine how symbols are extracted and which languages are currently missing or broken. Done means agreeing on an approach and adding reliable support for the selected languages.

Written by the indexing model from the issue text.