Hey Annie Kwok,
While I don't know of any automated way to create a custom message for downtime, I have a few ideas that may help:
1. Have a script that pings the view and sends out an alert to users if the page is down. (I'm not exactly sure how to accomplish this but I know other users have created similar systems)
2. Add a comment to the view telling users when to expect downtime or inaccurate data.
3. Republish the view with a text box informing users that the view may be inaccurate.
My guess is that the suggestions above don't quiet take the place of the feature you'd like to see. As such, I'd go ahead and submit a post to our Ideas section (Ideas) and have other users vote up the idea. It's a cool idea so hopefully it gains some traction.
Hi Diego, good idea to post on the idea forum.
I think all these details are somewhere stored in the PostGre sql database, we might have to to have permissions to access these tables and get the information. I am not sure but the REST API might help.