Filter on Link/Multi Select through Querry wriiten in PY files and called in Client Script

@mohitchechani and Friends I am learning, how best filter records can be populated based on server-side API response for filtered records on a similar link doc used in another doc type.

I found this, as most near to my search on the forum is Can not filter in Link Field - #2 by vinhnguyent090

I build API to push filtered records but not getting success as I am not clear on how to map query response. My JS code is here

frm.set_query('Project Milestone Status Update', function () {
    return {
        query: "bren_erp.api.pending_milestone_project",
         "filters": {
           "milestone": frm.doc.milestone

and server-side code returning the list of milestone masters based on the certain condition that should be clear

def pending_milestone_project(project_id):
		real_estate_project_detail = frappe.get_all("Real Estate Project",filters={"name":project_id},
		for row in real_estate_project_detail:
			milestone_name = frappe.get_doc("Real Estate Project",
			for project_payment_schedule_row in milestone_name.project_payment_schedule:
				if not project_payment_schedule_row.completed:
						milestone_name = project_payment_schedule_row.milestone_name,
			row["project_payment_schedule"] = project_payment_schedule
		return pending_milestone
	except Exception as e:
		gen_response(500,"Something Wrong. Please Try Again")

I am still a learner, so please help me , thanks in advance