It took some time but the Celestials were finally counterattacking and they were indiscriminate in their attacks. Instead of just targeting the Rifle Mages, they had sent energy powered attacks against their so called allies.
Jin believed that they were doing this similar to what Ress had been doing. They do not want the information to be dispersed to the rest of the kingdoms, and letting Ress take the fall if they are not able to defeat them even with the army that they had.
After all, the Mong Kingdom's Royals believed that their army would have surpassed every single soldier on that particular battlefield and with safety margins added into the calculation. However, they had never expected their Rifle Mages to be formidable enough to deal serious damage to their forces and the remaining grotesque looking angels were pushing out all kinds of power attacks in order to make sure there were no witnesses.