Simon 5 is coming soon!
Simon version 5 is currently in beta testing. It is a massive update, introducing a much-requested feature: syncing the Simon data between multiple Macs, plus a Simon Status service, a Link Checker filter, improved Find filter, iMessage and Speak Error notifiers, a new app icon, and much more.
Important: please note that Simon 5 requires a minimum of macOS 10.12 (Sierra), and will be a paid upgrade from Simon 4 after the beta. Purchasers since September 1, 2020 automatically get a version 5 license (that also works in previous versions).
Re: Notifier: Create a file
The closest Simon could do at present would be to email that text to yourself.
Though, you may be able to use a Report to do this, too - it'd always write the file, but it could include whether it was a success or failure. Reports don't have to be HTML; there are templates to do RSS or tab-delimited files, and you can easily create new templates.
In Simon 2.3, I want to extend the Script service to all it to be used as a notifier, too, which would allow custom notifiers like you want.
Notifier.
Okay, I dont want do use the mail feature, because if the mail server are down no notifier are sent.
One could send a mail from the Mac where Simon are running and then
set op a action to extract the text and send it as a SMS.
I made a work-a-round for sending the notifier as sms for now, but a 'notifier as txt file' feature would be nice.