I don't know if I got all of the discussion here. I find the OP confusing as on the screenshot there is Geany and Pluma but the text refers to different distributions.
Anyway and apart of personal preferences about this feature, the next release of Geany will contain the setting @elextr mentioned in https://github.com/geany/geany/issues/3564#issuecomment-1735263332 and then, @ineuw, you can set it to a very large value to disable ellipsizing altogether.
The new setting was introduced in #3365 because of #3344 and #2112.