Enclose the SQL string in double quotes, assign an empty string to param_end, and on the SQL string, enclose the param_end in single quotes,

Eg:

param_end = ""

stmt_insert_audit_record =  "INSERT INTO default.batch_run (task_name, start, end, status) values ("+param_task_name+", " + param_start+ ", '"+ param_end+ "', " +param_status+ ")"
  
spark.sql(stmt_insert_audit_record)

This could help I believe.