Keeping this in consideration, is coldheart trace rifle good?
Coldheart can do respectable DPS against bosses. This is the only Trace Rifle in Destiny 2 that is worth running in all content. It can deal solid boss damage in PvE and Gambit, and it isn't half bad at shutting down Supers in PvP. It's the jack of all trades for the Trace Rifle archetype.
Secondly, what does coldheart catalyst do? Coldheart Catalyst is the Catalyst of Coldheart. It increases Coldheart's stability and reload speed by 18.
Moreover, is coldheart better than Prometheus lens?
As I said, there's no real difference between Trace Rifles apart from the element they fire. Prometheus Lens uses Solar energy, which is arguably more obvious than whatever Coldheart shoots. However, Prometheus Lens differentiates itself with the second perk you'll find on it, Flame Refraction.
Are trace rifles good in PvP?
Trace Rifles really aren't the meta in PvP in any shape way of form, but if you insist, we'll recommend Ruinous Effigy once again, especially if you're playing something like Iron Banner or Control. It has an OK time to kill and you can then use the relic to slam down and one-shot anyone that you catch with it.