First of all, thank you for being a Twigmo service user.
Yes, the latest release of Twigmo add-on for CS-Cart was 1 year 3 months 12 days ago.
Technically, it is required to rewrite each CS-Cart function in the Twigmo add-on to adapt these functions to data format of Twigmo mobile service (Twigmo was designed as a versatile service for different ecommerce solutions). In other words, we need to code the second CS-Cart software and put it inside the Twigmo add-on to copy all the CS-Cart functions to Twigmo. Obviously, we never planned to do so and added only the most useful functions.
Now there is a responsive skin in CS-Cart 4 (and Twigmo can never repeat all its functions) and the number of CS-Cart v2, v3 users (they don't have a mobile skin out of the box) is naturally decreasing (they are switching to CS-Cart 4). In this situation, it does not make sense to invest time and money in further adapting the rest of CS-Cart functions to Twigmo mobile format. But Twigmo is not dead, it continues to render mobile sites for all its clients 24/7 and we have no plans to stop this service (actually, CS-Cart v2 and v3 users have no default alternatives to it). Also, Twigmo serves the default CS-Cart add-on Mobile Admin App.
If you use CS-Cart v4 (you do), yes, we recommend to use the default responsive theme.
I hope, I have answered all your questions.