Sorry I must have closed Steam before hitting Post Comment to this the other day:( There is not a way that I know of to increase those without doing so for everyone. They are only at that quantity as that works for me during testing. Too large of stacks was taking too long dumping items or increasing weight while I test items so I had to scale them down. Considering most people use a limited number of types of pieces when building, it might be better for you to spawn items in large stacks as you need them. Like:

cheat giveitem "Blueprint'/Game/Mods/AAMultiplayer/Castle/Walls/Straight/Basic/PrimalItemStructure_Stone_Castle_Wall.PrimalItemStructure_Stone_Castle_Wall'" 100 1 false

to quickly have 100 walls to place.