Spoiler Warning. First of all no the brazil locust swarm problem will not yet appear because the arc is not over. Secondly the locust invasion arc is far from over since the prince rabbit is yet to be revealed, the progs is not yet extinct, and even the ents constant harassing invasion is yet to be over (that blue moon ent was just a tip of the iceberg btw). And thirdly the theo slave annoyance typa thing thay people were talking about a few chaps is probably the unprofessional term of employee the reason i say this is because of theo constantly gaviny slaves, sejun somehow will gain the title slave king and since he got agitated by it later on he change its name to employee to become more resperctful (happens in 500+ chap in the novel). And to tell you the truth the amount of hate people gave to this manhwa only because the slave remark was overwhelming to the point the translator had to step up to apologized about the matter. (Felt sorry for him)

Yes the potential beings are yet to become apostle or disaster of destruction due to sejuns interference and of course cuengi is on this list. I am sure you already know why, cuengi is still small and growing and as he continues to eat sejuns crops and food which is filled with enhancements and power it actually caused cuengi to become more powerful than originally speaking. Because of this fenrir, the first apostle of destruction actually fount out that cuengi was the demon of destruction due to its immense. I dont know if cuengi will change because currently sejun is keeping cuengi in check and kind. Well for now.