Hi rarno1d and welcome to the Mattress Underground 
Happy to hear you had many good years with your Tuft & Needle mattress! Unfortunately, replicating any mattress is very difficult, without knowing the exact specifications and materials used. While Tuft & Needle do produce quality sleep solutions, they use proprietary formulations for their foam; and the mattress you want to replicate is no longer available, it’s an even trickier proposition. If you are referring to the 10" T&N mattress, I believe this version had about 3" of 2.9 lb high performance polyfoam on top of a 7" 1.8 lb polyfoam support core. Keep in mind that the specifics of components, fabrics, etc all contribute to how a mattress ‘feels’ for any sleeper, so there may be some difference in how comfortable it is for your current sleep profile even if you match the foam density.
You might want to do a forum search (you can just click the link) on T&N, As there are quite a few forum posts from members sharing their experiences of theirs mattresses around that time.
Keep in mind as well that any good supportive mattress will be based on your Stats (height, BMI, sleeping position(s) and any underlying health conditions) and your PPP (posture&alignment, Pressure relief, and Personal preferences), and also be aware that in the last year on another mattress, your sleep profile may have changed as you adapted from your prior T&N to your new ESW mattress…also, Latex and Polyfoam are VERY different feeling materials, so the ‘too firm’ feel may have something to do with the latex as well as firmness…and keep in mind latex is a much more durable and breathable material, as you can see comparing the Mattress Specifications You Need To Know to the Mattress Durability Guidelinesto see how certain materials will last over time. have you considered adding a topper with a softer feel to modify your current sleep system? This might save you a bit of time and expense.
All that being said, you might contact Trusted Member of the site MFC to see how practical it would be to try to replicate the T&N polyfoam densities, or online foam retailers like Foambymail to see if they have similar foams in stock. Whichever way you go, i wish you success, and please feel free to keep us posted on your progress!
~ Basilio