@doublemeat thank you for continuing to contribute.
Your two numbered points:
1. Of course you can try to persuade others to enhance Geany if you don't have the time or knowledge. If you persuade somebody, as I said, a PR that addresses the problem is welcome.
2. And thats a fourth workaround :) To paraphrase Stallman, the father of open source, "we make the software because we want to, we are happy if its useful to others, but we do not gain from having users, and we are sad but we do not lose if they use another tool".
The problem only exists if users don't use one of the published solutions. Saying "use a specific command line option" is not dogma when so far nobody has a solution that will still support Geanys current feature set, which as it is a lightweight IDE, is more complex than other plain editors.
A number of the contributors to Geany do so to support its use as a software development tool rather than a simple editor, (and I'm one) so their focus is on those features, not what they consider (wrongly in your opinion, but they disagree) a minor plain editor usage which has several workarounds. And several contributors have expressed the opinion that they won't ever use a full GUI IDE as root because its too risky, so they won't be fixing it.
It isn't clear if [gedit supports](http://linuxcommand.org/man_pages/gedit1.html) specifying which of multiple instances to use.
But isn't this seemingly "intractable problem" why c library functions like mktemp exist?
If you persuade somebody to make a PR have them read the comments above, that point out why that doesn't work.
To reiterate, part of a mktemp name is variable so multiple temp files with the same base can be present. But as it starts, an instance of Geany has to look for a _particular_ socket, not just _any_ socket, so a name that is variable isn't any use. Other issues around using the chosen config are also noted above.