I think 6.5x9 would be more usual than 6x9, but a 135mm lens on either size is odd---that lens would typically mean 9x12. The "/14" suffix on the filmholders should indicate the format; I looked in a 1931 Zeiss catalog and it seems that "/14" means 5x7.5 cm---for which an even shorter lens would seem apt!

In that catalog, the Trona was numbered 214 and available only in 6.5x9 (214/3) and 9x12 (214/7); a 1928 English-language catalog shows it in 3 1/4x4 1/4" only, with a 135mm lens, but doesn't mention the model number.

Beats me exactly what you've got here, but it's a gorgeous camera.

-NT