For Event Construction, you can use a Branch and for boolean make it Editable with Default value False.no connect your construction code to the True part. whenever you need to use construction just change it to true for your actor(you can select wall together and change it at once
for your Switch Problem you can use “all actor of class” and then for each loop and change them without problem
or use instance static mesh or hierarchical instance static mesh(hierarchical is better performance but if they frame rate come below 10 it hides instances otherwise it’s better than another way)