This patch shows off two things: the Stored Waveform Oscillator (SWO) and the Reverb package. While playing a few notes, the reverb time and high-frequency damping were adjusted by MIDI. (The various glitchy sounds you hear are due to the real-time adjustment, not the reverb itself.)
The SWO can take a formula giving the strength of any given harmonic. This patch uses this feature for two oscillators. The first has harmonics 1, 6, 11, 16, 21, etc., up to the top of human hearing. The second has harmonics 1, 8, 15, 22, etc., skipping by 7. These were simply found by experimentation to sound a lot like bells.
This is then run through a reverb, and as you should be able to see on the screen, the reverb speed and high frequency content are adjustable via MIDI General Controller 1 and 2. (All MIDI controls are usable from Moselle, but most examples just use General1-8.)
The reverb is not a built-in module type. Instead, it is a package. A package contains modules inside it, all wired together for a given purpose. In this case, there's a digital delay line with a lot of taps, and several filters controlling feedback damping and general tone. This package was written by us but the point of Moselle is that you can write these too. If you don't like this reverb, by all means write your own and share it if you want.
Note the sound is recorded directly from Moselle: no hardware or external processing was used.