Yep all those "Instant" abilities are pretty unresponsive. Using, for example, Swiftcast > Divine Seal > Medica II requires ~3 seconds of button mashing.
Or using Swifcast and then Raise right away will just cast Raise with it's normal cast time.

It just feels unfair how fast you have to react to the game mechanics at times, yet the game can't react fast enough to player's actions.