SetantaLP

I think the main reason for this bug is, that block-placing is handled on client and server (which also causes block-placement sounds to be played/the block to be rendered for a short time even if the server cancels the block placement.)

Yea, but I think it would be more consistent to place structure-files, that should override the ones from the assets folder, inside the data-folder as inside the structure-folder, where minecraft stores the structures-files you can load/save with the structure-block

Yea, but I mean that you may overwrite the structure-file by a mistake, when you want to save a structure and the file it is placed in folder where your saved structures are stored. If you placed it in the data-folder, this won't happen, and it also fits together with the loot tables.

It may be better to put them in the data-folder (world/data/structures/) like the loot tables, so that you can't override them by a mistake.

It seems that the bug is introduced in 1.7.3 by allowing Gui-Elemtents to rescale based on the font-height.
So one of the easiest ways to fix this issue, would be re-drawing the screen and automatically scrolling down to the selected language.