Since both IRC PRIVMSG events and PubSub/EventSub events are triggered for Channel Point redeems that include text, it would be really nice to be able to match them together using a unique ID.

While the redemption reward ID does match the 'custom-reward-id' tag of the PRIVMSG, which lets you at least match the redeem type, it'd be really nice to be certain the events are identical. You can kind of estimate a match using timestamps and/or user id & message contents, but there are potential cases where mismatches and conflicts could occur.

The easiest option would be to make the PRIVMSG 'id' tag the same as the redemption event 'id', but if that's not functionally possible, then adding an 'event-id' to the PRIVMSG tags or a 'msg-id' to the reward-redeemed event would be equally acceptable.