Melee buildings have 75% boost, range - 50%. That makes sense. These buildings appeared in game files more than a year ago. For now there is no appropriate recipes.
Both melee boosters are as usefull a pile of dung on a pavement.
The reason why the current boosters are so good is because you have first strike. this means that before your opponent can hit you you can cripple them so much that they are no longer a thread if a thread at all.
The weakness of LM and HM is that they are strong but always have the disadvantage of not hitting first.
Imagine this, there is a group with shotguns (archers with boosters) on 1 side of the field and a group of pikemen on the other side.
Shotguns are so strong that they can kill most of those pikemen before they can get close.
Now I can make those pikemen hit 100x stronger. if they get into range of the men with shotguns they can slice them litterally in multiple pieces.
The issue is that before thay can get there 90% or more of there unit is already dead.
Even if the few survivers survive win and slaugther those men with shortgun into pieces it's still a phyrric victory.
Now if we would give those pikemen kevlar vest they they might not loose 90+% but maybe 10%.
Now they can slaughter there enemy and most of them survive.
This makes the difference between a good and a horribly bad building.
It shows that the designers seem not to have a clue why LM and HM are soo poor in combat when boosters are taken into account.