Warning: More than 8 wadfiles are in use. (23)
This may be harmless, and if no strange side effects are occurring, then
it can safely be ignored. However, if your map starts exhibiting strange
or obscure errors, consider this as suspect.
Did you forget to put point-entities in your map? You need at least one info_player_start and one info_player_deathmatch and a light-entity.
Or maybe you accidentally put an entity outside the map?
Also make sure that you didn't make a single brush over the entire map (instead of a map ceiling, floor and walls).