I know they like reinventing the characters for this show, but I feel like making Mulan one of the bad guys would compromise the integrity of the original Mulan too much, basically making her a polar opposite, so I dunno that they’d go there.
In the promo for next week, It looks like she's ready to chop down the beanstalk, leaving Emma and Hook stranded up there. If she's working for Cora, and Cora needs the compass they went to get, it'd make no sense for Mulan to be chopping down that beanstalk.