The problem is techno-social. It is not possible to solve, no matter the money thrown at it.
1) It is not possible to make as small a vac with separate air flow for motor cooling.
2) When used for sanding, there is almost zero airflow, this makes it impossible to reliably cool a through-flow motor on a high duty cycle basis. A few minutes is fine as the motor takes time to to heat up. *)
3) Once you make a super-small vac that is mechanically suitable for sanding, people WILL use it for that, no matter how much you state to not do that => bad reputation, warranty claims, etc.
The only way around this problem is to take the full-scale CT MINI motor assembly and install it into a systainer chassis with a form factor of SYS 337 or so. Maybe even re-use the MINI/MIDI bags. But there is no way to make a long duty cycle vac in the original CT SYS form factor. Even the CTC motor unit is slightly bigger ..
Combined with the SYS-CART and CT-VA such a mini-vac would be very much usable even in a shop setting. But it will no longer be a vac you take up a ladder ..
On another tone, the CTL-SYS is still made and sold in Europe. That it is NAINA is a sales decision by FUSA I presume or that they are just selling on existing stock. Hard to tell. But it is marketed and available in Germany.
*) this is likely why the variable-suction CTC does not support the bigger batteries - it may be overloaded by prolonged use an 8Ah pack would enable. So why complicate the design to give that tool-destroying option..