The healer wand currently sets an entity's health to the entity's prototype's max_health, but where players are concerned (and possibly other character-style entities) this isn't actually their real max health, since there are both per-force and per-player health bonuses. I did some digging on the lua API docs and found that "player.character.health = player.character.prototype.max_health + player.force.character_health_bonus + player.character_health_bonus" will do the job, tested with the in-game lua console.

It would be nice if the healer wand could detect player character entities and apply this effect to properly reset them to full health, because currently it only ever gets you to 250 (base game max HP) even if you've used this mod to adjust your own max HP.

Looking at the code for scripts/magic_wand_healer.lua, I think line 169 is where the extra code needs to be inserted:

local max_health = entity.prototype.max_health -- For all entities in general
if entity.type == "character" then -- But players have individual and force bonuses to max health
    local p = entity.player
    max_health = max_health + p.force.character_health_bonus + p.character_health_bonus
end

Hey!
Should be fixed in the next version.
Thanks!