Currently enduring titles record only player kills, with no distinction between the kill being of a small ship or capship. If you kill the capship when its owner is not piloting it, you don't get a kill on the title at all.
Suggestion: Also count kills on player-owned capships on enduring titles, either as the names of the capships themselves or in a seperate heading with the names of the owners. So like:

These Capital ships have been killed by this ship:
"* Name"(1), "* Name2"(3)...

OR

These players' Capital ships have been killed by this ship:
Player(2), Player2(5)...

If there could be seperate tracking for Goliath and Trident kills, that would just be cherry on the cake.
Additionally, capship kills should be recorded similar to Queen, Levi and unrat dent kills. If you've damaged the ship and you're in the sector when it's killed, you get counted on the kill. This is because capship kills are often "stolen" by station guards or turrets when most of the work is done by players.

+1
Bump

So, FYI that we do have this in a planned TODO pipeline. I don't know when exactly, but we will take a look at this when we can.

This was implemented in 1.8.655, this past week:

- Enduring titled ships now record player-owned capship kills in its history. The owner of the Enduring ship must be in the same sector when the capship is destroyed.

Just curious, does this include queens and Levi's?

Not that I'm aware of, I think it's implemented as described in the patch notes.