By my opinion..the fact that you will be "tested" on a performance basis prior to be offered a LT is not a negative thing. (if you aim to stay in Air Baltic).
It means that if you'll be called for LT you have a slight chanche to be offered a contract in future (even if seasonal)..because you already fits the company requirement.
I don't think you have to pay TR and LT in advance so..if all goes bad you can always pay another organizations if you want to add that famous 500 hrs to your log.
Good luck everybody