Synapse aggressively rate limits (matrix-org/synapse#9487) adding rooms to spaces. On my homeserver 10 is the most I can do at once.

In Element v1.7.24.1 it looks like any failures to add rooms to a space do not get retried if the backend returns a 429. There is also no visible error to the user that the addition failed.

Expectation: Element would notify me if rate limited OR automatically retry.