This is a formal ticket of what Justin Edelson and I discussed earlier in December 2017.
The Jackson Sling Model Exporter needs to correctly set the character encoding so content can be correctly handled. It currently defaults out to ISO-8859-1 which makes displaying localized content impossible.
I have put together a sample project here: https://github.com/auniverseaway/sling-exporter-sample
This will show how the default JSON get servlet correctly handles the content, but the Jackson exporter does not. I have also attached screenshots of the behaviors to this ticket.
It sounded like Justin had ideas on where to solve this, so I will defer to him on where it should be done. If I can help implement a solution in the place you want, let me know. Internally, we cannot use the Jackson Exporter until this is fixed, so it's pretty high priority for me to contribute back if I can.