Igorrock already answered your question about Franz Thiele in Teplitz (Teplice, Czechia since 1945). I have nothing to add.
The gun was first proofed by an Austrian proofhouse in 1901. In 1927 it was nitro reproofed by the Weipert = Vejprty proofhouse. Maybe it was rechambered then from the 8x58R Sauer & Sohn to Wilhelm Brenneke's 8x72R, a slightly more powerful load? While the 8x58R was loaded with 31 gr T1910 powder and a steel jacketed 196 gr bullet to 1906 fps, the 8x72R used the same bullet ahead of 39 gr R5 for a mv of 2185 fps. 8x72R cases can be formed from 9.3x72R brass, sometimes available from Sellier & Bellot or RWS.
Both Teplitz and Weipert were towns in the Sudetenland, the northern part of Bohemia, settled by Germans since the middle ages. Before WW2 Teplitz had a 75% German speaking population, the Bohemian gunmaking center Weipert even 95%. All Germans were expelled or worse from Czechoslovakia in 1945. So it is near impossible now to gather any information locally.
While Britsh cape guns usually have the rifle barrel left, German and Austrian guns most often have it on the right side. Contiental Büchsflinten = cape guns are usually fitted with a push – forward set trigger for the rifle barrel. As the left barrel trigger is usually the rear one, close to the triggerguard, it would be quite inconveient to set a left barrel trigger.