Amazing!
"BR" would be 42 52...
Well... I tried the TFTP method with these firmwares from US and EU, and the result was a "bricked" device that I recovered by using the OpenWRT snaphot for my device.
So, I guess that, if the firmwares wasn't "accepted" by my device because "BR" isn't supported, I could change the bin file to artificially supports my BR device, and theoretically, it should work.
How much I could be possible wrong? 
UPDATE: actually 42 52 is there... so no binary change is necessary.
The only thing left now would be the skip value, if any.
From the US firmware version, I found these values:
fwup-ptn fs-uboot base 0x01000 size 0x0d45b
fwup-ptn os-image base 0x0e45b size 0xe6eda
fwup-ptn file-system base 0xf5335 size 0x6606e5
fwup-ptn soft-version base 0x755a1a size 0x00059
fwup-ptn support-list base 0x755a73 size 0x001d5
fwup-ptn extra-para base 0x755c48 size 0x0000b
fwup-ptn profile base 0x755c53 size 0x02dae
fwup-ptn default-config base 0x758a01 size 0x02329
fwup-ptn partition-table base 0x00800 size 0x00800
Is it possible to calculate the skip value from this?