Several users have contacted me about the same issue with WP-Cumulus this week. On non-English (and mostly European) language blogs some of the tags would display either very small or humongously big. This turned out to be caused by internationalization of numbers in the inline style sheets in WordPress’ tag cloud. I have no idea why this only popped up now, but the Flash movie wasn’t built to handle 9,55pt tags (instead of 9.55pt).
Version 1.17 fixes this issue, and adds a highlight color setting.
Oh, and Ryan Tomlinson has ported WP-Cumulus to BlogEngine.NET. More about his project here.