Hi Elisabeth,
The alt tag issue will be fixed in the next theme update, regarding the issue with the H1 tag we need to check your website back and as it should be shown.
In order to assist we need to check your website from the back end, please install this 3rd party plugin “Temporary Login Without Password Plugin” which allows us to access your dashboard without sharing access details.
To better understand how the plugin works, please watch the video guide below: https://www.youtube.com/watch?v=EMu0e78OpJo
Please make sure to mark your reply as private to hide it from the public.
Kind Regards