Tempering appears to be an active thing. Its not something that just happens from being close to a primal. If that was the case, the Company of Heroes never would have had a chance to kill one, let alone two, primals.

Further, I suspect tempering is something that requires the Primal to use Aether so generally I think Primals only do it when necessary or when they intentionally want to. I point to Garuda's attempt to temper the WoL as well as Ifrit. It was an active thing.

For this reason I wouldn't be surprised if the Goblins aren't tempered. Either Alexander isn't aware enough to be tempering at this point or it feels no need to temper the Goblins who summoned it.

The other alternative is the actual Primal may be the central component of the Fortress. I wouldn't be surprised in the least to discover that the actual primal is the heart of the structure rather than the structure itself in the same way Odin uses a host.