There's a mechanism for tuning how OSM shapes are simplified before being rendered in our maps. This query accepts a $3 parameter to control the simplification tolerance, see postgis documentation here. We run kartotherian with allowUserQueries enabled which should turn on code paths that allow the request to include an override for "arg1" (default 0.001) to tune simplification, but it seems that the guard condition sense is reversed, so that sending "arg1=0.01" will throw an error that the value is invalid, yet "arg1=abc" throws a different error demonstrating that the parameter *should* be a float.

Shapes seem to be much more complex than required in many cases, so this investigation is to determine whether the default value can be tuned, and how much effort it would be to make the complexity threshold parameterizable directly from the mapframe tag.