Try this. It is a free ware. I have used it in a scenario similar to yours. The time difference in my case was +9½ hours. Lightroom did not have the ½ hour mark. Only complete hours. So I resorted to this. Works like a charm.
https://www.bulkrenameutility.co.uk/Download.php
On the lower side you have options to change time stamps. On clicking "Change File Timestamps a window opens up
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© herculeorama [SHARE LINK] THIS IS A LOW QUALITY PREVIEW. Please log in to see the good quality stuff. This is the window where you change time stamps. Delta is where you enters time in Days, Hours, Minutes, Seconds. Click Negative if you need to go back in time . Leave blank to add. And after doing that you click on OK button and then the Rename button on the main screen.
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© herculeorama [SHARE LINK] THIS IS A LOW QUALITY PREVIEW. Please log in to see the good quality stuff. Very easy to use and a very useful utility I use often for renaming files too.