The I9100T rom shouldn't be a reason for TA not working, there's nothing special in the rom that would prevent it from working; apart from very slight difference in power output of radio, the I9100 & I9100T are exactly the same phone, and the only difference firmware-wise (slight) is the modems (I had a I9100T on Voda for 2 yrs).
Have you asked in the TA thread on here ? (Search for it). Also, a few other ways you might be able to attack this, and bear in mind there is risk of turning your phone into a paperweight involved here (And frankly, for the sake of a warning triangle at boot, why risk it ? I mean, who honestly sits there staring at their phone as it boots ?):-
*You should be able to find the 'old' bootloader if you search for it, if you flash it, you'll be able to reset the flash counter & get rid of the triangle with a jig. However, this may render your current rom unbootable (bootloop), which you'd need to fix by flashing the 'new' bootloader (again, easily found by searching) and flashing a bootloader is the most risky flash you can do.
Not so much because the actual flashing of the bootloader is risky as such, there's no more risk so far as the flash itself is concerned. It's just that if the flash goes bad (which is a very small risk with every single flash), you won't be recovering it. It's not like flashing a wrong kernel that ends up in a bootloop which you fix by flashing the right kernel or a stock rom & you live happily ever after.
It will be a service centre or bin job.
*Maybe try flashing the 3 part stock rom linked to in Hopper8's 'Odin troubleshooting' thread stickied in General (this will wipe your phone), then flash a JB a stock rom for your carrier & try TA again ? May not make any difference, but if it means that much to you...
Again, given the hassles to do this, you seriously need to ask yourself is it worth it just to get rid of something you see for two seconds when the phone boots & is purely cosmetic. And also bear in mind using TA is not without risk, though 'complications' arising from its use are rather rare, they're not completely unheard of. My take on using TA has always been (across several devices) 'Try it once, if it works smoothly first time all good, if there's any drama whatsoever, don't risk it a second time, etc'.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Failure to search is the leading cause of male impotence on XDA
If you don't know how to recover if things go wrong, what are you doing flashing custom roms ?