OpenNMT can also run amok given totally unreasonable input too (example below). I'm being unfair, but the more serious point is that translation systems might go crazy in less obvious ways. While fluency is greatly improved, they certainly don't always get the meaning correct. I'm excited to see what people will do to better diagnose when we can trust the translation.
Input: "Toll ach toll toll ach toll toll toll toll toll toll toll toll toll toll toll toll toll toll toll toll toll toll toll toll Deutsch."
Output: "Tell me great great, great great, great great great great great great great great great love great ? ? ? great love ? ? ? ? ? ? ? great ? ? ? ? great love ? ? ? great great ? ? ? great great ? ? ? great great ? ? ? great great ? ? great great ? ? ? great great ? ? great great ? ? great love ? ? Good ? ? ? great love ? ? great love ? ? Good love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? great love ? ? Good ?"
[Each ? was a musical note glyph, but HN ate the unicode character.]