The spell costs in this mod are controlled by the vanilla cost reduction perks. Even though Ordinator removes them from the skill trees, it leaves the original perks present in the game. So with Ordinator, the spells impacted by this mod will never receive the benefits of the half-cost perks. However, you can get around this by re-adding the perks to your character with the console. This won't impact the cost of other spells, as those are only paying attention to Ordinator's new perk system.
You could even take it a step further with one of my favorite mods, Exciting Skill Ranks:
https://www.nexusmods.com/skyrimspecialedition/mods/13067/This has an option that will automatically add the relevant cost perks once your skill reaches the appropriate level. Since they will be added by a script, it doesn't matter that the perks have been hidden on the skill tree. Effectively, this mod will be doing the work of adding the perks by console for you, and doing so at an appropriate level to maintain the balance of your game. While this doesn't make my mod work perfectly with Ordinator, since it still won't have the more granular cost reduction that Ordinator's perk tree offers, it will be relatively balanced.