Is your Blender version at least 3.4? The generator will not work with older versions because it relies on newly introduced nodes.

If that didn't fix your issue, feel free to message me with a detailed problem description and I'll try to replicate and fix it.

An array of flanges on the corners may appear if your fillet radius is very high, and thus the length of the individual corner edge segments. The reason is that the corner edge length is used with a statistics node to evaluate where to place the flanges. To prevent this, reduce either the fillet radius or change the seed, path resolution, input geometry or random offset amount.

If pipes intersect and create glitching artifacts, this is likely caused by a too high random offset value, which can create overlapping edges at times (even though I tried my best at limiting the maximum offset amount to minimize this issue). Slightly reducing the random offset amount will fix this.

Appendices can appear even if the pipe mayhem parameter is set to zero (they almost certainly will appear when pipe mayhem is activated), because of the way the path finding algorithm treats the proximity to the input mesh. A slight change in input geometry or path resolution will usually fix this.