[@catchamber], I would offer the strong suggestion, in addition to those hard limits, having a closer interpretation of "Read As Intended" (RAI) versus some of the "Read As Written" (RAW) usual tricks and the general Gentleman's Agreement I referred to. That way we are not seeing anything from Diplomancers, Planar Shepherds, Red Wizards, Dweomerkeepers and the like. The builds are almost universally transparent and recognized now too, so it would be easy to say, "That's not really appropriate, do you think you are X, Y and Z, really?"

That's not to say a character should not be allowed to invest heavily in Diplomacy, or a warlock prevented from going binder so they can then prestige into Hellfire Warlock to do powerful Eldritch Blast casting, or a sorcerer from being a Swiftblade/Abjurant Champion/Spellsword/Dragonslayer and so forth. Just that the over intent is to provide a standard of "Reasonable optimization for the purposes of roleplaying an archetype rather than optimization for the purpose of raw power."

That and I would play cards like what you described with magitech and psitech close to your chest as the Dungeon Master. Artificers, especially Psi-Artificers do not need any added help or incentive.