The mail merge functionality is constantly being enhanced. In 5.1 mail merge embedding was released - see here: https://archive.fosdem.org/2016/schedule/event/libreoffice_m...

You can track changes in LO also - starting in 4.4 it has been progressively getting better - see here:

https://wiki.documentfoundation.org/Track_changes

Curious about the font issue... I've never tried to use Asian and Roman glyphs on one line before. But multilayout is a bit of a mess and is constantly being worked on.