Greetings! After I tried some other advancement-type mods, I stopped on this one!
But one thing I missed it's "Criteria" bar that shows "what left to do to complete an advancement"
I know, looking at your mod name it sounds needless or so, but just consider this request.

Also I prepared some design, how it might look like. Other mods uses "side-bar" screen to show criteria, but I came up with something more tooltip-looking one.

But now I'm thinking it will be hard to implement scrolling mechanic in tooltip

Something like that is already builtin (tough not so pretty, just displaying the internal requirement names)
You can see them when having advanced tooltips enabled, or by tweaking the config to always show them

Oh, I see right now! Hmm, I just making advancement tab for my modpack and attempt to make it pretty 🥴

But I don't know how overhaul Criteria screen without a lot of work for you...
I tried again to combine our designs, but there anyway a bunch of things to do:

• Place criteria panel inside advancement tab frame
• Place criteria panel below hovered advancement
• Adjust width of criteria panel to match advancement width
• Convert sneak_case into regular text -> golden_carrot = Golden Carrot
• Hide or Make it switchable through config [Group:] and "minecraft:" text
• Sort entries by alphabet -> "A-Z Uncompleted then A-Z Completed"

OOf, and to perfectly match Minecraft text-style all / some of entries should be translateble somehow...
I don't want to bother you with it, but maybe it would possible to implement at least a few of these features 😵

I'm sorry it's all about my perfectionism

Your mockup looks great!
At the moment I am pretty busy porting all my leftover 1.20.1 mods to 1.21 and do not have too much time on my hands, so I am unable to implement it myself.
If you can get that implemented I will happily release it for everyone.