So, i have found this in the config from "All the overhauls" (But your mod Merging Chests Unlimited still are broken):
I comment out it
--wide chest
--if mods["WideChests"] then
-- overwrite_settings("int-setting", "max-chest-width", 27)
-- overwrite_settings("int-setting", "max-chest-height", 27)
-- overwrite_settings("int-setting", "max-chest-area", 27)
-- overwrite_settings("double-setting", "inventory-size-multiplier", 1.0)
-- overwrite_settings("int-setting", "inventory-size-limit", 500)
--end
So for me as an workaround i set all 42 in file too 400
BUT all what i do. Ingame its also the 27 limitation. I have absolte no idear why. I have tested it also in the editor with a new game.