I just checked and it doesn't seem any of these were written to really work with the web UI as they lack the "hgroup" and "vgroup" UI organizer statements almost completely.
Here's a little delay program I wrote
import ("stdfaust.lib");
delayLength = 1.0;
filterDelay = hgroup("Delay", delayBlock)
with
{
delayTime = vslider("Delay time", 0.10, 0.01, delayLength, 0.001) : si.smoo;
delayFeedback = vslider("Feedback", 0.10, 0.01, 0.99, 0.001) : si.smoo;
lowPass = vslider("Low Pass", 5000, 500, 10000, 1) : si.smoo;
highPass = vslider("High Pass", 40, 20, 2000, 1) : si.smoo;
filterBlock = fi.lowpass(4, lowPass) : fi.highpass(4, highPass);
delayBlock = +~(de.delay(ma.SR * delayLength, delayTime * ma.SR) : filterBlock * delayFeedback);
};
process = _ : filterDelay : _;
Here's how it looks in the Faust web editor:

and via the browser from bela:
