I only know of a way to index logs up to a number of days and not specific dates, but maybe we can fool it for a while.
1. If you want the logs to be indexed on the MDS-HA you'll need to put them in the appropriate directory in CMA from the MDS-HA in the same domain. All CMA, from primary and secondary MDS are functioning as log servers as well so where it will be indexed depends only where it's located.
2. Since you keep indexes for 60 days, older logs would be indexed if we try to include the logs you want to index in the range. I think that you can move those log file to another folder temporarily so it won't index them as well.
3. Follow the SK for indexing older files - https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solut...
Be sure to disable retention for index files, otherwise it will delete them.
4. After it indexed them, you can follow the steps in the SK to return the value of number of days to index to the default value and put the logs file back.
I think this should give you the desired outcome.
Kind regards, Amir Senn