All KSDSCST records have a date in their key (position 2-5, length 4)..
You can select all the records that have the missing IMS environments on date and afterwards add them again with the APCIAM44 for these specific dates...
Every date has a S, V and T type record (position 1, length 1).
You need to remove them all..
To add them again with the new IMS region information, run the APCIAM44 job against the data again.
It's also possible to run the APCIAM44 job against a new KSDSCST dataset and REPRO the output to the current one, after removing the old once from the current one..