I prefer Abiword instead of Libreoffice, so i right-clicked on an opendocument-file, selected "open with" and in the window I chose to make it open with the command "abiword", and when I double-click the document it opens in abiword, but in the launcher it shows a gray question mark instead of the abiword icon. It's a minor thing I know, but it bugs me. How can you start it and have the real icon show?
Have you tried to, instead of opening a document, open Abiword through Menu > Applications?
- open AbiWord from your applications menu (Super + A)
- once AbiWord is open look to see if its icon is present in the Launcher. If not, I don't know. But if so you can right-click this Launcher icon and select the Pin to launcher option
- now try opening a document and see if it uses the "?" icon or the AbiWord icon.