I tried to have a look at the sport field/pool issue, so I downloaded one of the areas you mentioned. But I can't reproduce the issue. Also without seeing your entire script it is hard to see what is going on. Might be one filter is missing a condition which causes them to be included.
Sorry for my very late response, real life constraints prevented me from playing with AFS
I've tried the Crispy's technics to get some infos (ExportOGR|osm_way_id=XXX) but the log files were almost the same, no real difference (tags are sorted differently).
Anyway I found the guilty command by feeding scenProc with an OSM file which contains only one element (a swimming pool). Then I run the script and saw in the logs the exact command which was generating a building and it was:
CreateAF2Building|NOT building ="roof" And FAREARAT>0.7 And NOT building_levels="*" And NOT height="*" And FAREA>=200 And FAREA<700|2;3|1|gable|residential|0
This is a stupid command because the conditions are too permissive. In fact I was thinking that only building elements was taken into account by CreateAF2Building. But apparently it's not the case so if there is a NOT building ="roof" condition there must be another condition with building_levels or height, which was not the case in my command.
So the problem was in scenProc but in my brain
Now I have to find time to play with the Crispy's V7 scripts and the latest release of scenProc.