However there is a massive hurdle in getting just a basic overview of the titles applicable for the award. Published in german within a 18 month period or whatever the criteria specifically is.
From the SdJ website:
"The jury will consider all new family and adult games published during the current and previous calendar year."
As a practical matter, while that remains the rule, it has been a _very_ long time since a game released early enough to be considered for the SdJ in one year has been nominated or recommended in the following year.
Also, you can add "in Germany" after published.
Is there any resource/website/blog/geeklist that keeps track of the titles that go into it all?
No - or rather, certainly not that I've ever found. Given that it's all games released in 2014 and 2015 in Germany (not even for the first time, necessarily), it's a nearly impossible list to create.
However, for a not unreasonable approximation, you can use the Spiel 2014 Preview and Nürnberg/New York 2015 Preview.