Depending on the citation style there either are or aren't any spaces between the actual citations and the text on which they follow. Just compare the Nature style which has superscript numbers (e.g. "as shown by Darwin1") with some generic author-date style (e.g. "as earlier shown (Darwin, 1834)").

When you already have written a manuscript with the Word plugin, but want to switch styles (from a style with these spaces to one without, or vice versa), you have to delete or insert all these spaces by hand. I recently circumvented this problem in Reference Manager by using an customized author-date style with a leading space before each citation (so the citation field shows as " (Darwin, 1834)" instead of "(Darwin, 1834)"). This allowed me to switch easily between different type of styles without having this problem.

My question was whether an option to provide such leading spaces in the citation field could be provided for those styles that require spacing. Perhaps it could be included as a preference in the Word/OO-plugins? It would require some logic to distinguish between the two types of styles: whether separating spaces are used could either be included as a parameter in CSL, or it could be deducted from the use of brackets (I can't recall having seen any bracketed styles that don't use separating spaces).