Since I cannot find Flandras or other theoretical forms (Flandra and Flandrum), I assume that the creator of the article simply adapted the Modern English Flanders.
I did a quick search and Bosworth-Toller does have a line of OE ("Hí heóldon ofer sǽ tó Flandran", which can be found in the last line of VI. in this entry) that mentions Flanders; it appears to be a singular weak noun rather than a plural strong noun, but that's all I can find in B-T.
Hopefully, there is some reference to Flanders that has the name in the nominative. If not, I guess we could make something with a form of Flemingas.
What say you?
- þancunge Espreon,
Interesting question, I thought I found the form Flandras somewhere on the net, that's why I used this name for Flanders. But now I can't find it anymore and instead I found Flandrum. So I think you're completely right on this. In Icelandic it's Flæmingjaland so maybe Flemingaland could be an alternative for Flemingas? Anyway, I'm pro renaming the article. --Þunaraz (talk) 17:04, 14 Hrēþmōnaþ 2014 (UTC)