Damge bonus vs. Gremlins may or may not be worthwhile depending on how good you are at hitting them with Alchemers. I do not expect you to have tested this already with your Elemental ones, but I guess if you can hit Devilites easily you're more likely than the average player to have a knack for hitting Wolvers and Gremlins.

Damage bonus vs. Beast is only worthwhile if your loadout is such that you don't have anything much better than a Shadow gun against Beasts- unlikely for most players. You'd have to have the knack and neither a Piercing weapon, DPS-oriented bomb, nor a sword that's not Elemental since either of those would be much more appropriate assuming you're basically proficient with it.

For future hunting, the general rule for all bonuses vs. monster families is, if the monster is vulnerable to the damage type it's worth keeping since that's half of the main targets unless there's a special problem. (for example, your bonus vs. Gremlins IF you have a hard enough time hitting them that the weapon is useless against them anyway) If the damage is neutral, it's very context sensitive (based mostly on the rest of your loadout) and if the monster is resistant it's almost certainly wasted since you'd have to make a serious loadout error to be forced to use it against that monster type.

ASI and strait damage bonuses are usually good since they're always working for you, while CTR is very good for bombs and context-sensitive for other weapons. (I'm assuming you cannot get ASI on bombs.) Here the general rule is that ASI and strait damage work best for softening a weapon's weakness (thus ASI for slow weapons and DMG for fast ones) but is still often useful for boosting a weapon's strength, while CTR is ONLY good for boosting a weapon's strength- if the charge attack is crap, or just not good for you, CTR is not gonna give you any benefit.

Added status effects are even more a matter of personal taste than the other bonuses, in addition to being sensitive to a bunch of other things, so I don't know if there are general rules other than that Curse is really awesome. Sleep is a useless status effect, but the developers removed the chance to end up with a Sleep UV for that very reason. If you ever get Curse UV on any status-aura bomb, you have yourself one nasty overpowered monster of a weapon- so much so that I'd not be surprised if the developers removed that from the UV results table too... Actually, a spammy weapon with chance to inflict Curse OR Sleep would be rather interesting since monsters regenerate HP when asleep. Thanks for the idea, Merethif!