Glad you like the mod!
But now the muzzle flashes and personal lasers spawn a full head above the character.
Muzzle flashes should have been scaled as well. But I'm not surprised it doesn't work correctly: The game doesn't know any character other than the default one. Naturally, the shift vectors of all vanilla guns are based on the default character as well. But custom characters may come in all sizes, from tiny to huge (see, for example, genshin-impact-skin) – and even at a zoom factor of 100%, the flash may be off.
Adding a setting to control the muzzle-flash offset may work if you know that you'll only ever have one character mod installed. But there simply isn't a setting which would fit multiple characters if they differ in regard to size and shape – and if miniMAXIme is active, the default character still exists and might get weapon offsets that don't fit. The offset is defined in the prototypes, so it can't be changed at runtime.
The only way would be to make custom weapons for each character variation. This would require that all character mods provide info at what position they expect the gun. But then I'd have to exchange guns as well each time a character is changed – and I'm afraid there will be even more problems: What if a gun is put into a chest and then used as ingredient in the recipe of an assembling machine? If it isn't of the expected prototype, the assembling machine will be blocked. But we only have events for changed player inventories (ammo, armor, guns, main, trash), changes to other inventories go unnoticed. The only way to notice that a special gun has been added to an inventory would be to keep track of all inventories (chests, machines, vehicles) and check their contents in regular intervals. Any mod doing that would be a UPS hog par excellence! :-D
So: I could provide a setting, but it would be an ugly hack that works only if only in single-player games where the player always keeps the same character.