I’m using Ubuntu. In the Libre Writer search box, accented characters wipe out everything that goes before. If you type québec, you get qu, and then the é wipes out the qu, and you end up with ébec. The only way to type a word with an accented character appears to be to write it in Notepad and copy and paste it into the search box. This is a rather foolish blunder by Libre Office!
*The reason is that the AltGr key used to compose é and other accented characters highlights everything in the search box, so when you press AltGr and é, you find first that everything in the box has been highlighted and then that é has replaced everything in the box. One solution: don’t use Linux. Or don’t use foreign characters. But seriously…