thanks for the all who help in this forum ,i have succesfully done the srilankan update for honda crv 2018 aussi model
steps
1. update the prevailin aussi maps as describe by the https://honda.garmin.com/honda/site/generalInstructions follow the instruction and see the video as well https://static.garmincdn.com/autoOem/honda/docs/en.pdf
https://vimeo.com/176223246/324d0e0f5a
after that install garmin express software in to your pc as in this pdf instruction https://static.garmincdn.com/autoOem/honda/docs/en.pdf
then after aussi update complited come to your pc and go to this site and downlord the srilankan map as a img file http://garmin.openstreetmap.nl/ (it save as (gmapsupp.img) it is about 58 mg } select
Mapnik
Country as Srilanka in the filling
then replace the same file in the usb which is a 42 mb file
now again go to the vehicle and do the update process after starting the vehicle
now you are done