I am bad at full thoughts evidently: do read on timezones and DST though so you don't hit any traps - https://docs.intersystems.com/iris20251/csp/docbook/DocBook.UI.Page.cls…

It appears in your example you need a better way to determine if you are in DST or standard. You can't just go off of month and you also might be dealing with a region that doesn't acknowledge DST.  

USER>s time=$tr("abcd-ef-gh ij:kl:00","abcdefghijkl",20250518144529)

USER>w time
2025-05-18 14:45:00
USER>s time=$SYSTEM.SQL.Functions.DATEADD("hh",-6,time)

USER>w time
2025-05-18 08:45:00

This comment shows a quick way to convert to ODBC 

https://community.intersystems.com/post/convert-numeric-expression20201…

You may have to tweak a little.

USER>w $tr("abcd-ef-gh ij:kl:00","abcdefghijkl",20250518144529)
2025-05-18 14:45:00