yeseo should be making more verbalizations/vocalizations at this point. at her age, (going on 1.5 yrs), yerin was very vocal and babbly. not making a whole lot of sense mind you, but at least there was a normal amount of vocalization there, which indicated ongoing language acquisition. yeseo can now say a few words apparently, but from these videos she seldom spontaneously babbles or mimicks parents' vocalizations, which at this point in her development she should be doing plenty of. bobaeparents should keep an eye on that.