An active contributor for this blog, Mr. nos_com71 was kind enough to notify me about a firmware he found. It is from Polkomtel, a Polish telco. You can download the package from this link @ Norton Zone cloud. I had issues with the download, but using a different browser on another machine solved it for me.
I didn't install the firmware into my s-12, but as usual, I extracted it and confirmed its contents and version of V100R001C69SP103, which is quite new. In the Bjørn Grønli's spreadsheet the newest one he found is a SP102, but this Polish one seems to be a notch newer.
If any of you test this one out, please tell us about it.