Insert doesn't work with VisualEditor and 2017 wikicode editor (Wikipedia, MW)

[Eccenux]

The VE Wikicode Editor (also called 2017 editor) uses the VE surface. Results should be roughly the same.

VE actually uses many editors, that doesn't seem to be feasible to do with any browser API.
VE Wikicode Editor seems one contenteditable. So that might work... But probably won't either.

Results for wikicode on Windows (Firefox) are similar to #1.

• Multiline: Two lines are added in-between all selected lines. Changes are not registered (previewing changes doesn't show inserted tag).
• Singleline: Seems to work fine. Both when single word is selected and many items within one line (image below).
• No selection: Works fine.

Note for testing make sure library is loaded on Wikipedia.

mw.loader.load( 'https://pl.wikipedia.org/wiki/MediaWiki:Gadget-sel_t3.js?action=raw&ctype=text/javascript' );

Then use code from #1.