Hello,
It is actually uncommon of me to answer questions quickly, being busy making product and all.
At any rate, there was--at the time of the WizKids Dark Age game--an effort to nail down the various figures to a set scale (N-scale). The table shown in the Technology of Destruction uses the figures to generate the comparison chart. In theory, that should make them accurate....
Only, well, the figures didn't all wind up at the scale they should have (the Cougar is a 35-ton chicken-walker design; it's profile should be much lower than that of an 100-ton upright monster like the Atlas).
Final answer: No; they are not canon.
Thank you,
- Herbert Beas
BattleTech
Catalyst Game Labs