i got everything to work to create a specific npc but i cant seem to be able to add a sprite face when they talk, maybe i missed something? could you perhaps make a quick tutorial on how to do it?

For everyone that has a face currently, they use a bespoke cutscene init script instead of cis_polyliner_npc. But it's very simple to add.

Add a new variable "my_face" to obj_npc_polyliner which has type "expression" and default value NONE:

(this is the variable you'd change in the room editor for the NPCs that should have faces; you'd do it the same way you update messages but use the name of a face sprite instead)

Edit cis_polyliner_npc to pass on the my_face value to the dialogueevent's face_sprite:

And finally a stupid change, edit obj_shopmenucontrol's Step event at line 214 to set my_face to NONE before calling cis_polyliner_npc. It really shouldn't use this function but I was lazy so I reused it instead of making a new one for shopkeeper dialogue, lol.