Hello @gisela,
If you have directly added your custom code in the original theme file then all of your modification will be lost once you update to the current version of the theme.
So you need to always go through the child theme for any modification in the original parent theme. In this way, there won’t be any problem in updating to the latest version.
So, we would suggest you to build the child theme and add all of your custom code there.
Hope this helps.
If you have ay query/confusion related to the theme then kindly let us know.
Thank you.
Best Regards!!