It's true what you say, as far as I remember Windows 7 and 8 builds were build on a daily basis, except on Saturday and Sunday...
anyway, I had a close look to this site and found newest articles out of 2010. So I cannot imagine that he knew about a W8.1 build line at that time. @Misaki of course Microsoft engineering team works on builds every day and when the hot phase is there, they certainly produce such builds even on Sundays. But this I think was not the point as he said latest build is 9401
What else could tobiastimpe have said ? He has no source at all it seems - and is assuming build numbers by guessing.
have a 2nd look at it: he compared W8/German version with W8.1/current build which is English only. Afaik, there is a Polish lp but not sure on this
thats right first pic is windows 8 pro german that i have as MainOS and win 8.1 blue as VMware player image.. ive posted this two pics becorse the removed menus to show.. i hate this
somebody probably just DISM'd the RTM LP into the ISO or something. There shouldn't be an official standalone LP yet.
Tobiastimpe answered my other question about Polish lp, which has nothing to do with your original post of the two different language versions. I saw the polish layout somewhere but have no idea, how it was done: here the pic