Hi Gerd
there are two places in the source that filter the data: In ProblemListProcessor.java we select on relations with one of these types: WANTED_RELS = {"restriction", "multipolygon" ,"through_route"}; Other relations are not passed to the keep-complete routines. So, yes, type=multipolygon relations are handled by the routine.
Reg. performance: please see this thread: http://gis.19327.n5.nabble.com/splitter-relations-to-be-checked-with-keep-co...
In this thread Wanmil wrote: - Shouldn't boundary relations like multipolygons be complete in the tile? Yes, but... Adding all related boundary data to a tile increases the tile size very much and makes sense only if the boundaries are used as polygons. At the moment we don't know anybody who uses boundaries as polygons but lots of users use them as lines to display the border names. Since I render only type=boundary & boundary=national_park as polygon (not all boundary=administrative) is it possible and not too much work to add this rule to the keep-complete process? I dont think there are too many of them in OSM that it will affect the performance. As workaround, I could grab all of those relations and put them in the problem list with osmfilter or overpass api.