Improve NER label results on Non-English text
One approach you can take is Multi-Task Learning. This approach is a little more complicated but tackles your problem in hand.

The idea is that you train a neural network to perform different NLP tasks. For example:


Translation
Part-of-speech tagging
Named entity recognition
Chunking


or any other task.

However, you might have data for translation (e.g. Spanish to Latin, or English to Latin), you have data for NER in Spanish and English but not for NER in Latin.

The theory and studies behind Multi-Task learning suggest that if you learn a task with that language, translation for example, you can get better at other tasks as well, NER for example.

So you can learn NER in Latin by learning NER in other languages and learning translation, chunking and POS tagging.

This should take care of your lack of NER data in Latin.