I haven't seen this solution mentioned yet so thought I'd sign up and post in the hopes that it helps others.
If you're having difficulty setting a hot word with PocketSphinx because of the "non-english word" error, you can simply add it to the dictionary. The dictionary file is named hub4.5000.dic
and can be found in the following directory on your phone's primary storage:
The dictionary is a text file and consists of a list of words in alphabetic order. Next to each word is a pronunciation key. Adding a new word is just a matter of inserting a new line in the correct place and defining the pronunciation. The pronunciation key is separated from the word by a tab and each syllable of the pronunciation is separated by a space. Getting the correct pronunciation is the tricky part as the "sounds" may not be entirely intuitive. Luckily, there are plenty of words in the dictionary you can use as a reference. You could also do it via trial and error.
For example, I wanted to add the word "Anita"--she's the hot android from the show "Humans"--so I inserted the following line:
Save the file. You can now make "anita" your hot word in Open Mic+