Probably not. Hallelujah roughly means 'Praise our lord' (or thanks to our god, praise our god, etc ).
This is usually for monotheistic religions, where Celstium is polytheistic. Most importantly it's a fictional religion, and I'm trying as much as humanly possible to keep it differentiated from mainstream religions that actually exist.
Such as that Celestium doesn't offer salvation in the afterlife in much the same way it doesn't offer damnation either. It promotes worship of the gods, but without being extremely strict. You can worship all of them, or just a single one. Believers are encouraged to worship in their own way. Whether this is burning incense and meditating, offering thanks to your patron deity on occasion, or building a pyramid of skulls as an offering.
The varying gods govern different aspects of the world, and there are different approaches to attempting to gain their favor. One might offer a quick prayer to Tiel with the rising sun in the hope of maintaining order in their life, where a superstitious trader might rub their talisman of Mendal against another coin in the hope of making some good deals.
Ultimately there is surprisingly little structured worship, even for the same deity.
But it's mostly to avoid being associated with actual religion and religious practices. Most of that was for shameless clan promotion. I doubt we will come up with a 'clan cheer' for the start/end of matches. But we'll have to see.
