Hi Sebastian, no problem. Likewise feel free to DM me. Yes, the F5 failover part is normal, and yes, updating any AWS routes automatically will require an API call. If you don't want to let the HA iApp set that up for you, you could script yourself. Consider this out of scope of this article, but you'll need to consider:
a) you need to make a AWS API call to update the specific routes you have
b) you can do this using a AWS cli command from a Windows or Linux box that has Internet access
c) you should have some failure detection mechanism so that you can run this script when it is required.
Obviously it's easier to let the HA iApp set this up, but if you have other non-F5 things to do at the time of failover, like update your application, then you could script this as part of your whole recovery activity. However, if you don't already use the AWS API for your own processes, I would recommend just using the HA iApp, especially to start with as you learn.