Table Top is, and always has been, the core framework. If lore contradicts what is available according to TT rules the lore is wrong or out of date (per the order of supersedence of canon by the line devs that they follow). If anything, the novels are now deviating. Pretty sure the temporary name change had no bearing on this.
I would say that is true for when it was originally created but not later on.
Anything over the last 10 years should be deemed a new version if they wish to rewrite canon (this game was done carefully to give the narrative some context to the Battletech universe for the Bullshark).
Sort of like how Castles Brian has not really replaced the older lore.
In quite a few ways it is the books that created the narrative from a universal framework given to the writers.
As an example the William Keith wrote several notable books within the Battletech universe and was also involved in game design and worked at FASA, in some ways the TT did not gain traction until such lore and fiction was created; had early adopters until then and sadly the games/fiction are still not what one could call mainstream popular even today.
Anyway all writers have to follow a specific lore framework to remain with the requirements of their contract, I mentioned before how even such well known writers such as R.A Salvatore do not have complete freedom and he has mentioned how he would love to write certain specific characters/situation in the Forgotten Realms universe but it has not been accepted as a project by the IP owners.
It also comes down to the definition of canon lore but also what could be called a universal framework that ties everything together for projects involving that IP.
What created in detail the narrative for Grey Death Legion and fleshed out other mercs, ComStar in detail over many fiction books,Helm memory core and how that slowly influences the universe in the books and also NAIS same concept, fleshed out the great houses, the clan invasion,etc.
The lore can be seen as defined in the TT manuals, games, and also the universal framework used by the books, each has their foundations but how they are implemented and importantly used means whether they can be consistent.
It is easier to maintain a consistent universal framework/lore with fiction because it has much less interactive demands compared to games even TT, a broader market, and less branching in terms of how evolves over the years.
Is there something particularly contradictory you feel in the fictional lore between Gray Death Legion and up to say 3065 putting aside game mechanics and interpretation by authors (which still need to follow a framework)?
TT and the PC games for me tend to deviate due to players' interests/interaction/freedom to create scenarios; this can happen in TT and really can be seen with PC Games as we have sort of seen even here with discussion between those saying it does not feel like 3025 or the weapon/rare mech type proliferation for the era.
Over the last 10-15 years I am not sure which of the three (fiction/TT/computer gaming) could be perceived as the current primary driving force for lore/canon material as it applies universally.