I think that some of the strategic resources can be abit to few and far between and can just completly ruin a civ if it doesn't have access to one or two of them to build a unit (such as priest of leaves, ritualists, the rarely seen stonewarden) and leaves the game much more up to chance on what kind of random numbers generated the map.
Here is what I suggest, make it abit similiar to warrior axemen macemen and some golems, where the resource isn't required, but gives a boost.
Gunpowder: resource -25% construction cost to gunpowder units, or just remove gunpowder as a resource.
Regeants incense and gems: -25% gold upgrade cost, -25% production for units effected by it, +25% production cost to priests, or instead free promotion with resource.
Perhaps also only required to upgrade from conjurer and mage to summoner and archmage and priest to high priest.
Iffy changes: Iron golems -50% production with iron, increased production cost 40%, doesn't require iron, possibly add stone and gold golems.
Here is what I suggest, make it abit similiar to warrior axemen macemen and some golems, where the resource isn't required, but gives a boost.
Gunpowder: resource -25% construction cost to gunpowder units, or just remove gunpowder as a resource.
Regeants incense and gems: -25% gold upgrade cost, -25% production for units effected by it, +25% production cost to priests, or instead free promotion with resource.
Perhaps also only required to upgrade from conjurer and mage to summoner and archmage and priest to high priest.
Iffy changes: Iron golems -50% production with iron, increased production cost 40%, doesn't require iron, possibly add stone and gold golems.