Hello,
I tried entering the code you sent me but then the entire offcanvas-menu got affected, I guess because the menu items are also connected to ".offcanvas-menu .offcanvas-inner .sp-module". I'll attach an image of how it looked like.
How it looked like after entering the code you sent me:
[https://ibb.co/0QfY6zL]
I then realized I could just add {flex-direction: row !important;} to the "ul.lang-inline", instead of to all the different ".offcanvas-menu .offcanvas-inner .sp-module" (which would affect more than just the flags of the language switcher). So I did so and got the following result:
How it looked like after altering the code you sent me and only using a certain part of it:
[https://ibb.co/VD2Gy5v]
Before I asked for help on this forum I had entered "ul.lang-inline{flex-direction: row;}" in the css files, but that didn't work. Although now I know that the code that was missing for it to work was to add "!important".
Long story short, now it works. Thank you!