If you replace the text using a keyword replace add-on the CSS will still change the case of itNon custom addon path:
Step 1. Use CSS to convert all sentences as you want it to be.
Step 2. To handle acronyms, use one of the many keyword replace addons on here so they are capitalised etc. You will need to feed all the used acronyms into the addon though. Keyword replace addons are a must have anyway with most having link attribute properties to redirect your users to other knowledge sections within a site.
In some case could be useful add a class to messageText (if the user is in a specific usergroup) so this can be used on specific user that use only CAPITAL LETTERS.I think I got it working now.
Thanks for the hint Mike .