I think that you being new to handloading, you shouldn't worry about 'burn rate' charts. They are in fact meaningless, because a powder burns completely differently inside a cartridge to the way they get their 'burn rate' chart information, it's called a 'callorimeter bomb'.
In fact, powder 'burn rates' vary depending on the pressure that it is loaded to, and the expansion ratio of the case it is loaded into, in other words, the size of the case capacity, compared to the size of the bore.
I wouldn't try to 'match' factory velocity in your rifle, it simply will not be likely to be able to achieve, they use 'blended' powders which have their 'burning rates' TWEAKED to match their published ballistics, which you simply cannot do with the canister powders we are able to buy.
My best advice is to try the 2 powders you mentioned and go with the one that is more accurate, higher velocity is neither here nor there when hunting is concerned, game animals never know the difference between 3000fps and 3200fps.
Just for your information, Retumbo is quite a bit slower than RE22 and may not work as well in the small case of the 7mmRM, but wonders never cease. I think a good powder would be RE25 if RE22 is not up to scratch.
Good luck, and good hunting.