Regex for {{cite source}} find and replace[[edit] | [edit source]]
Find: ''\[\[(.*?)\|(.*?)]]''
Replace: {{cs|$1}}
N.B. for anyone else reading: Some old style citations are, shall we say, non-standard, in their use of italicisation. This only works if the citation is in the following style:
([[STORYTYPE]]: ''[[Story title (dab term)|Story title]]'', etc.)
If the italicising quotes are elsewhere, like spanning across multiple links, fix them first or the regex will lose stuff.