There are three sorts of notes in the legato patches:
- Start notes
- Legato notes, which include the transition material
- Repeat notes
It's the second of these that you are finding too short. There are two things that you can do:
- Keyswitch to a sustain
- Cut the preceding note short, cover the gap with the sustain pedal and then play the next note (which will force a start note, which is longer)
DG