Unfortunately, looks like FSNav will never be updated. But for those who haven't purchased it, here is some good news (from FSNav support forum):
i am steel around but now have decided to move from fsnavigator onto good
my time with navigator is been very good and i thanks you all for your wisdom
and helping during the many years of programme building.
I can longer no more offer any assistance but i am leaving the programme
to be downloaded free from next week onwards. there will be only the one
registration code withing the download which will allow the programme to
be used in full. Thank you all again and good best wishes for the future