The desire for this feature is a symptom of a deeper problem: the accuracy is really bad!
Initially your test estimated I know 60 words. I tried again on a new email and it estimated 300. Both are far too low, especially if you're counting multiple verb forms, as such estimates often do.
For reference, I took two years of high school Spanish, am level 19 on Duolingo, and it gives me a count of 2000 "known" words. When they had the Immersion feature, I could read large portions of articles in the Spanish-English direction. Sure, maybe I don't have strong recall of all 2000 of those words, but IMO your test has to be way off.
Using a different email is a really bad solution. I don't want to have to guess what email I used for this 2 or 3 years down the line. No thanks.
I specifically left Duolingo to try out this app because I felt Duo wasn't challenging enough. I'm not willing to grind boring material forever.