Thank you for the illustration.
I don’t know if it helps but I will comment on what I am seeing.
We are in Linux. When clicking on the savegame.tsvg file from the browser the “You have chosen to open-dialogue” appears. The tsvg-file is unknown and there is no Helper Application for it.
This is the expected behaviour. As I said before, neither TripleA nor tsvg-files are in any way registered with your Linux-OS. When you execute the triplea.exe using WINE in Linux, you just launch the Java-program TripleA using a windows-launcher. Instead you should use “Save file” in this (above mentioned) dialogue to download the savegame and manually load it from inside TripleA after starting TripleA.
You use TripleA.exe for Windows to launch the Java-program TripleA with Wine in Linux. So far so good.
You have started TripleA and want to load a savegame. You do not have or cannot find a tsvg-file in the shown directory/folder.
If you had chosen “Save file” in the first image’s dialogue, you would have the savegame inside the folder, that you would have defined just before saving. In the shown “open” dialogue, just change to the directory/folder indicated for saving and your tsvg-file will be there.