Previously, I've avoided keeping old switches around whenever I've swapped them in my boards. I'm realizing now that this puts me at a disadvantage when it comes to possibilities like this.

What do you use for switch storage to make this manageable?

I'll give the U4Ts a chance, too! They could be a nice fit here. Since I only need the lighter switches in a few keys, the spring swap doesn't even feel like much trouble.

I think we don't want the silents here since the person I'm gifting this to prefers a longer travel distance, and dampeners shorten the throw. Thanks for alerting me to that detail!

Should I look for springs on Amazon or are specialized keyboard shops a better bet for those?

I did order some Box Jades! The person I'm building this keyboard for did like a board I have with Box Whites, which afaik have the same spring. Given their preference for extreme tactility, the Box Jade might be perfect for them as a lighter complement to the Zeal Clickiez. :D

Box Royals have previously felt too mushy for me on a full board, but they might not be bad for extra light pinky keys.

Silent browns will I think not provide any discernable feedback to the typist I'm building this for, hehe.

Truthfully, I've not tried many MX-compatible switches in a full board. Just Box Whites and Box Royals, besides the Box Navies. My daily driver is a Model M.

I haven't tried the U4Ts! They're on my list of candidates. Do you find them to be pretty good as a relatively light switch that still gives good feedback?

I do have some Emogogo Silver Grays which I think might be comparable, but I need only a handful of these switches so I wouldn't mind ordering some U4Ts if they're good.

Spring swapping is a good idea, especially since I don't need a ton here. I wonder how light I can go with the Clickiez before they have return issues... maybe I could lighten those a bit.

The metadata you want is called a Software Bill of Materials, and there are a range of tools for generating them. Some generic ones include Trivy and Grype, but you may also find some for your language ecosystem by Googling ' + SBOM'.

One tool you can use to view these versions with a web UI is OWASP Dependency-Track.

All of the tools mentioned and linked above are F/OSS.