You can force some assimilation if you have a profession with only dutch pops, or can create one via NF. e.g. if java has only dutch officers, you can use NF on officers to turn javan bureaucrats into dutch officers, and then NF on bureaucrats to turn dutch officers into dutch bureaucrats. However if there is a javan officer pop then the bureaucrats will just turn into javan officers and it won't work.
Democracy from monarchy requires a Jacobin revolution.