Right now, if a query gets 0 results and has a Did You Mean (DYM) suggestion, results are shown for the DYM suggestion. If the DYM suggestion has ≥ 3 results, that blocks any cross-language results that would result from language identifications.
Loosening that limit from < 3 to < 5 would slightly increase cross-language recall while maintaining high accuracy. (See write up from T174116, namely the "Block Less, Show More" section).
Investigate whether the DYM result limit and the original query result limit can be decoupled, or also investigate whether increasing the limit for original query results also makes sense.