Thanks a lot for all of your feedback. And yes, I am also the maintainer and founder of HeidiSQL's code, so there's no need to worry about copyright.
However, the size of the application's icon is too large. See attached screenshot. In addition, opening the Preferences dialog takes a little while and can hang the application. It is also not possible to change the interface language, the only option is *** Auto-detect.
Yes, the icon is not only too large, its colors are also broken. I probably need to use a 48x48 px png instead of the 256x256, and another bit depth.
The languages .mo files are installed when you use the .deb package. I thought localization is not important to have at development time. But I guess I should drop a note near that drop-down, saying I could not find any .mo files.
And yes, I also noted the (short) waiter when opening the preferences. Smells like slow code somewhere. Will have a look.