Having insufficient privileges within the tags info-visualisation and info-visualization, I am not able to suggest synonyms. However, if we keep those tags separately it will take even longer before anyone will be able to edit. I suggest adding the two as synonyms for infoviz.
How to do this? Or who to ask?
(Pardon me for asking here on Meta. I was, however, not able to find any other place to raise the issue, and it certainly does not belong on the Main site.)