The Sustain function in electronic keyboards takes the place of you holding the keys down, therefore, how the sound behaves when you release the Sustain pedal will be the same as the AEG (Amplitude Envelope Generator) setting you have for the RELEASE Time.

This is a critical setting for any emulation sound. Too fast sounds unnatural, as does too long a Release.

In the AWM2 (Sample Engine) you have control over the AEG on a per Element basis, as well as at an overall offset level. This means you can manage the AEG at a very detailed microscopic level, and/or with a general ADSR offset that will affect all the Elements together.

If you start programming from an Init Normal AWM2 - you will begin will Waveform 0001, with an “organ” Envelope. Organ Envelope is immediate On, full volume until Key-Off where it is immediate off. While these defaults are pretty standard, they are far from what the ear wants to hear for a piano wave. A piano has a percussive attack... this means it is loudest at the beginning, It decays to a point where it can “sustain”, before it dies out. If you do not hold the key, the envelope proceeds to the Release segment

The two at the top are the AEG for Drum sounds
The bottom one is the general shape for all hammered, struck or plucked type sounds... including piano. See where Key Off occurs, the Release Time controls exactly how quickly the sound dies out. Key Off = Sustain pedal released.