The titans misjudging there weapon ranges seems to be a known bug.

But i have also noticed it with the scout ships aswell, Specifically with the reveal mines ability. They get almost close enough to do it and just sit there.

Having titans in a fleet with other ships seems to push the formations of the other ships around. This might be by design.
However because the titans have large weapon radius the other ships tend not to get close enough to fight. Which is kinda nice because they can be used to defend the Titian from smaller ships, but normally means the spend half there time trying to stay in formation when the Titian turns because the formation is spread so far apart.

Loving the game so far though!