It is no quite clear. I have four Cities, four traz around level 70 or so. i have watched the troops traz adds each day. they are not proportional.
They may vary as much a s 150% of one and 50% of another. And it is never due to 'leveling out' the least or most. it is random. Adding a second building for any troop will probably not increase that troop as much as one hopes.
Well, sorry, but it is clear. Easily demonstrable as noted at the end of this post.
Traz is random based on each troop collected as a proportion of the number of each type of barracks in the city.
If you have lvl 72 Traz you get 70 troops with each one of the 70 independently and randomly determined based on the proportions of the barracks in the city.
In the case of the OP orignally having 1 RH and 1 other barracks type, in the long run half the troops will be Rogues.
If the OP adds a second RH and keep the one other barracks then in the long run 2/3 of the troops will be Rogues.
As noted, Traz has easily verifiable behaviour. At 70 troops per day you can gather 2000 samples per month. Annotate daily the number of each troop type collected. Run one month with 1 RH 1 other barrack, one month with 2 TH and 1 other barrack.