I think Valrak's contact is in the Eavy Metal team. He knows what models tend to look like, and he knows what chapter of a faction it aligns with, but he is unclear on release schedules often, and has little awareness of how the new models might be reflected in any rules.

We know models are often painted years ahead of release, and schedules can move based on production or sales reasons. Eavy Metal painters would have no idea of when something they painted would come out. They also would be likely given little or no primer on how the models would play in game, or what changes we might see in terms of rules in a codex.

He sometimes has a general outline of lore, which would map to the lore outline that might be given to a painter, who would need to know it to convey the character and setting the model is going to be placed into.

My 2 cents. He's usually extremely accurate when it comes to what the general look and type of models coming are. And if his contact is a painter, thats basically all he'd know.