See notes on TextCat Internal Quality Control for explanations of maximum returned languages and results ratio.
Try different ranges for max returned languages and results ratio, other than the default 5 and 1.05. Should perhaps be set on a case-by-case basis. Look at numerical limits and proportional limits for max returned languages—some sets of languages are so small that it's hard to hit the limit.
If this is consistent across wiki test sets, determine a useful default. Otherwise, add as an option to be found at language optimization time. Update Perl and PHP versions of TextCat.