For Interactive to be less reliant on a ton of mesos for upgrades, maybe allow them to consume Spell Traces (or something) to discount the mesos cost of things like Star Force Enhancement and the like. This would come with something like while Frenzy Totem is active (in Interactive Worlds only) will reduce mesos obtain final multiplier, for example, by 70% - which means you would obtain only 30% of your default mesos in exchange for a lot more monsters which equates to more EXP and items.
The familiar thing is to improve the system and make it more interesting with extra line options, which is also shared across all worlds so it doesn't change anything for heroic. As long as you add in Glowing Cards and Bright Cards into the game then you make familiars function the same as cubing, improving the system while also simplifying the dumbest system from their current form.