They aren't Random really either. They are whatever they were set at for that round of RGs. WGT change the RG set about every 3 or 4 weeks. So that one will be tourney as long as it exists. It actually gives you a good chance to play in conditions you will be playing very soon. When i was Legend almost all the legend tier RGs for a while were on champ speeds. Made the move up relatively seamless.
Agree would be better to have it in the game client window before you buy not after, but i guess the way that WGT looks at it, when yu play real golf you don't know exactly what speed the greens out on he course will be playing. They can stimp a few and tell you what it is stimping, but that will likely be in the morning after they were mowed, so if playing in the afternoon they won't be rolling the same with the sun and growth etc. Even if you practiced on the practice green still doesn't mean the greens on the course will be the same. However, I do get what you are saying. I would prefer to know that stuff too.
Wait til you jump in a tier based RG that has the tees moved up. Your looking a the scores wondering why they are so low and one day you throw caution to the wind, or maybe you have had a few too many, and you throw you hat in and you're a legend playing from the Pro/TP tees. That info cannot be found anywhere.
Good luck at any rate. The wild world of RGs can be very addicting but immensely frustrating, so be prepared.