Hello,
First:
Unfortunately there is differences between the original hardware and Matrix 12 V manual. I found this manual a long time ago on the web.
It look like LEGATO in Matrix 12 V work like described in the Original manual, but not like described in Matrix 12 Vs manual.
In Matrix 12 Vs manual the LEGATO is described to switch legato mode between glissando (stepped) and Glide behavior. This is'nt the case.
I think it work correct in Matrix 12 V, and the Matrix 12 V manual is incorrect.
The switch between Glissando and Glide behavior is done with the KEYBOARD selector in the VCO's in the PAGE 2 section of Matrix 12 V.
Then to the issues:
As example in the following: When KEYBD is set as LAG input and LAG is selected to create pitch Glissando or Glide/ Legato (Portamento) in the Page 2 VCO sections.
According to the original hardware manual,
1. then a Lag Rate of 63 should in LINEAR mode give a portamento time about 30 seconds per octave.
2. In Exponential mode (LINEAR deselected), then a Lag Rate of 63 should give a portamento time about 55 seconds per octave.
There is clearly something wrong with the time in this mode in Matrix 12 V. It's far from 55 seconds.
3. A Lag Rate of 63 should with LINEAR and TIME selected provide a Portamento time about 55 seconds no matter the interval between the start and the end note.
Also here the Matrix 12 V has a to short time.
4. Exponential mode (LINEAR deselected) can not be used together with TIME. So the TIME button should actually not be visible unless LINEAR is active.
You are correct that the Lag Rate difference between values especially 52-53 is too high when LINEAR is active and TIME is not. This must also be a bug.
You can contact Arturia support directly through your account and report issues.