Yes anvils of Doom are a military secret.... Lighting runes on stone definitely aren't. Even just visiting one of the old holds would tell you that stone anti magic bias has not stopped the dawi from putting runes on it. Actually we knew they had a network, we found out about it. We also had a suspicion about Kislev but their not a elder race so it doesn't really matter.I feel like you are missing the fact that before the paper on Anvils of Doom in the Karak Eight Peaks expedition humans did not even know what Anvils of Doom could do, so no it is not general knowledge that Runesmiths could make stone more porous to magic. That is not a thing that anyone not a runesmith knew which is why Thorek looked pained all conversation.
As a rule of thumb if you have to pry something out of a runelord one syllable at a time the colleges of magic did not know about it. Hell before just now no wizard not named Mathilde or Panoramia even knew there was a dwarf Waystone network that was separate from the elven one... or a kislevite one.
And Thorek looked pained about basic knowledge. The whole situation goes against anything a runesmiths learns. It's airing guild business outside of guildhalls. It would probably pain him to talk about his favourite chisel if he used it for runes...