I looked at the package and it calls a language translation interface,

https://github.com/terryyin/translate-python/blob/master/translate/providers/mymemory_translated.py#L23

https://mymemory.translated.net/doc/spec.php

The description of this interface does not indicate minimum length.

You can test it by requesting the interface directly:

https://api.mymemory.translated.net/get?q=%3Cuntranslated%20text%3ESubscribe%20to%20the%20channel.&langpair=en|es