Giving this the 5.0 milestone because it works in Svelte 4 - likely because since #11371 we get more properties (which fixes other bugs that Svelte 4 has), so we need to enhance that list we have

Some of those also are kinda different from draggable...hidden for example is a "boolean attribute": you can't set hidden="false", it will still be hidden because the attribute is present. Same thing with inert even if it's correctly set as false it will still be inert. Same autofocus.

Also contenteditable seems to actually correctly reflect the value even in your screenshot.

We definitely want the change for translate and spellcheck

You're right, those are actually correct, and setting them to the string false is different to setting it to a boolean (or falsy) value.

I also don't quite understand the problem with translate and spellcheck - what is the problem with them? The look correct.

So in summary, all of those are actually fine?

You're right, those are actually correct, and setting them to the string false is different to setting it to a boolean (or falsy) value.

I also don't quite understand the problem with translate and spellcheck - what is the problem with them? The look correct.

So in summary, all of those are actually fine?

translate and spellcheck have probably the same problem of draggable...they are setters on the element so if you try to do element.spellcheck="string" it treat that string as a truthy value and set spell check to "yes" even if the string was "no"...the fix is the adding those attributes to the list of attributes for which we always want to use setAttribute. All the rest seems fine to leave it like this imho.