It seems to be a very long time to convert only 12 4 car units, when the HST refresh programme was done back in 2006 they would have been finished by now and ready for testing.
There was a long period of limbo in 2019 where they couldn’t progress ETCS fitment as the safety boffins at GW weren’t happy with certain elements of the DVI (Driver/Vehicle Interface), and Bombardier had to go away and rethink their design philosophy. That caused the slip from planned intro in December 2019 through to later this year.