Right now, we don't sync redaction events, which means it's possible to, say, join elections that no longer exist.
Unfortunately, it doesn't seem like it's possible to filter redaction events that only redact events that are not filtered: https://matrix.to/#/!NasysSDfxKxZBzJJoE:matrix.org/$l4ot1PPe1F86uB1sWkOpYOhVcMMURnFFjpq66obypCc?via=matrix.org&via=privacytools.io&via=amorgan.xyz
Hopefully v3 of the sync endpoint of the client-server API will fix this: https://matrix.org/blog/2021/05/14/this-week-in-matrix-2021-05-14#dept-of-spec-