Checked on this Lanbitou 3059 again today and messed with the cap. Taking the screw out of the inside, the middle of the finial comes out and that releases the clip. So I filled up the entire finial and around the clip with UV cure resin.
Before I could blow into the cap and could feel air moving through, now I can't. So we'll see if this stops it from drying out after hours.

This seems to have worked perfectly. A day later, the Lanbitou 3059 had no sign of drying out. Started writing immediately.
I'll keep an eye on it, but that's already miles ahead of how it was on arrival.
Update:
Welp, the Lanbitou 3059 fix didn't last. The entire top cracked and is barely attached.
I'm not sure if it was the extra air pressure, the resin compromising the plastic, or something else. Also I don't think the resin I used got 100% cured, which may have contributed.
If I had it to do over again, I should have removed the exterior clip entirely and just plugged the hole. I think it added stress.
So $3 and some time lost, not worth the hassle to try again. Could be worse.

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