If you look in the page source, you can usually suss out most of the stacks. Just quickly looking, I see labels for:
Doobox Notes
Yuzool Icons
an Extra Content stack
and then what I presume are your standard column, text, etc stacks.
That’s just the homepage though. (I noticed the ‘Collections’ page has others by Will Woodgate, Joe Workman, etc. You might have to look at the source page by page…
I wouldn’t worry. The site’s already responsive and I’m sure you’d be able to work out which stacks were used - looks like TopBox on one or two pages - without too much trouble.
Depends on what they want to update I suppose. Looks like it’d be fun!
Keep in mind that WeaverDetect is not updated for several years and does not detect recent stacks and plugins.
It usually detects modern themes (by looking in the right place, I guess)
It sometimes can be a useful tool as it proves in your case.