The Catalyzers are heavily, heavily dependent on landing multiple charged shots on the same target in order to detonate them all at once- and that's just to keep up with other guns, damagewise. You could try making the case that the explosions make it effective for dealing with clustered enemies, but in spractice what ends up happening is that when you need to stack your shots on ONE target, the OTHER targets will get in your way, making it even more difficult to meet your intended damage quota. Meanwhile, your teammates are just smacking the enemy normally and killing them long before you have enough orbiting shots to detonate for worthwhile damage.

Two suggestions for dealing with this:
1) Switch the functions Catalyzer's normal shots and charged shots (Normal shots orbit the target and are detonated by charged shots).
When you need to pump out more orbit-shots than detonator-shots, this seems to make more sense to me.
2) Allow Catalyzer explosions to set off orbiting Catalyzer charges on other monsters (i.e. allow "chain reaction" detonations)
This way, it's no big deal if another mob in the cluster ends up wandering to the front. You can still detonate them all at once.

When you look at swords, you may notice that their charged attacks are rarely just "One Big Slash!" Their charged attacks do something different than the normal attacks (often combined with the One Big Slash for good measure). In comparison, most guns' charged attacks are basically "One Big Bullet!" and no further function. As it stands I can only think of 3 guns with charged attacks that act differently from the normal attacks: Pepperboxes and their pull effect, Alchemers and their bouncing shrapnel, and the aforementioned Catalyzers. Even the Antigua series suffers from this, as it's got you standing still for five regular bullets and THEN fires the One Big Bullet.

Many sword-based charged attacks have gun-like functions that the guns don't have...
Brandish series has its recently-improved shockwave (which even newbie swords now have),
Sealed Sword series has its penetrating projectiles,
Snarble Barb series has its shotgun burst.

Why not add some of these sword functions to enhance the One Big Bullets we have now? Suggestions:
1) Allow the Blaster's charged attack to penetrate and score multiple hits (which goes well with the Blaster's defining knockback benefit)
2) Add penetration (it's Piercing!) and a series of Brandish-style shockwaves trailing the Magnus' charged shot
3) Fire the Antigua's five normal shots as a shotgun burst that accompanies the One Big Bullet/Birdie (allowing it to be useful against Wolvers))
4) Add Brandish-like chain-shockwaves to the charged Pulsar shot's impact, continuing on in the direction that the shot was originally heading (perhaps no shockwaves for the 2* version, 1 shockwave at the 3* version, a 2-shockwave fork for the 4* version, and a 3-shockwave fan in the 5* version)

On the flip side, can we give the Cutter series' charged attack a strong knockdown/flinch component on every hit like the Autogun's does? It's kind of a bummer to unleash a charged attack on a Gun Puppy and have it shoot you dead halfway in because your weapon won't make it flinch. Swords can afford to get some gun functions too!