Actually, in this case I'd say contact CZ-UB in Prague and see who they recommend for after market trigger reach reduction kits in Europe. I will say I have a CZ P-09 that had the "touch" by Cajun Gun Works, and while the difference looks small, the feel is really there.. As you say, US Customs is very wiggy about gun parts coming in or out - the trouble I had getting a 20 round vz-58 magazine in country was insane...the CZ-UB shop might have access to parts you or I can't get a hold of, and would know the legality of sending it to Estonia.
Good luck!
BTW, as stupid as this sounds - do you run the gun from the half cock notch? Is it decocker or safety model? There is a half cock notch for both, and the gun is designed to be carried there. Reduces reach and travel. Like this.