A rather janky workaround for this is a recursive event.
I have implemented this as an array of World Soft Object References so that it updates as the files are renamed but you can do the same with an array of string.
You can’t directly create an array of World Soft Object References. You need to add a Load Stream Level node and right click the level input and promote to variable and then make it an array. No idea why you can’t just directly create it.
Call the event with an index of 0 to start it.
I believe each iteration of the for loop doesn’t wait for the level to be loaded and load stream level must finish before it is called again otherwise it is ignored.
With the recursive solution each successive iteration is only run when the previous one has finished.