Wikimedia Bugzilla is closed!

Extension needs review before deploy. However, I believe StringFunctions explicitally won't be enabled in it's current state

do you have any other suggestion for #replace: function?

That depends. What do you intend to use it for? The string functions shouldn't be used if you can help it. As Tim noted in r51497:

Set this to true if you want your users to be able to implement their own parsers in the ugliest, most inefficient programming language known to man: MediaWiki wikitext with ParserFunctions.

WARNING: enabling this may have an adverse impact on the sanity of your users. An alternative, saner solution for embedding complex text processing in MediaWiki templates can be found at: http://www.mediawiki.org/wiki/Extension:Lua

#replace it will useful for month name translation in input texts of templates also for many frequency inputs that they can translated in templates.
if activing http://www.mediawiki.org/wiki/Extension:Lua is possible it is much better :)