Sadly, firmware.mobi seems broken for all "Samsung Galaxy Tab2 10.1" devices and firmware versions.
I uploaded two different stock firmware versions for the GT-P5100 model (similar to the GT-P5110 model, but with an additional 3G radio). For one, I uploaded the boot, recovery and cache separately together, for the other, the boot, recovery and cache in a Zip file. The uploads were successful, and the respective boot and recovery files are now available for download from firmware.mobi.
However, attempts to generate/download the CFAR packages for either of these GT-P5100 firmware versions gives the following error message :
Current status: ERROR
Estimated wait: NOT APPLICABLE
So, turning to the pre-existing related GT-P5110 model firmware versions, I attempted to generate/download the CFAR packages for about half of these, with the same resultant error message.
I even chose the IML74K.P5110XWALD2 firmware which has an available CF-Root package at the legacy autoroot.chainfire.eu site, but alas, the same error.
Yet I am able to generate/download CFAR packages for my Samsung GT-N8020, so the problem is specific the above mentioned new GT-P5100 firmware versions and the pre-existing (so presumably, once working) GT-P5110 firmware versions.