Hi Tobi-wan_Kenobi
I enjoyed my coffee thanks.
"Torpedoes are too cool not to have" - Totally agree.
I made a post not long ago detailing some ideas for how torpedoes could work, and for the most part, our basic ideas are very similar; Big, slow, partly guided projectiles that are armoured against PD and can do serious damage to even big ships. I love the mock-up you made and having energy bars "fill-up" a torpedo is a great idea too.
Torpedoes vs Shields
I like the fact that you've highlighted the similarities between Torpedoes and Railguns, they're both long range, high alpha weapons and IMO Torpedoes have more in common tactically, with railguns than with missiles. So to make Torpedoes really distinct I'd like them to find a role that no other weapon fills. Railguns are the long-range ship killers, but what they're not so good at is getting past shields. If Torpedoes could fill this role, it would make them very frightening to big ships indeed.
Given a large enough AOE, a Torpedo explosion could reach a target even beyond the range of its shield, damaging and destroying edge components and even the shields themselves. Another way a Torpedo could 'get past shields' would be to simply allow them to fly through shields undamaged (talked about a shield phasing device I described in my post).
Torpedoes and guidance
I really like your idea to have Torpedoes 'target' something only after a delay. Of course, Red October taught us that this is a thing because otherwise, Torpedoes might target the ship that launched them. I'm not sure how a Torpedo would decide what to target in cosmoteer, would it be the nearest ship? or the biggest ship within a certain range? or the biggest 'heat signature' (most powerful engines), or whatever target is in front of them when they activate? something else?