How to rename Photos with Apple Scripts?

GraphicConverter or a Better Finder Rename can do that via the GUI.

I have used YYYY-MMDD-hhmm-ss file name pattern for 20 years and occasionally do that also with exiftool to images with:

exiftool -m -P -fileOrder5 FileName '-FileName<ExifIFD:DateTimeOriginal' -d '%Y-%m%d-%H%M-%S%%+2nc.%%e' .

...and to movies with:

exiftool -m -P -fileOrder5 FileName -api QuickTimeUTC=1 '-FileName<QuickTime:CreateDate' -d '%Y-%m%d-%H%M-%S%%+2nc.%%e' .

I do wish there were a way to copy the Title into the Exif capture date.

It is possible to copy filename to metadata dates, but as you said earlier, the operation must be done before importing to Photos:

To copy filenames to metadata dates in movies and images choose GraphicConverter 12 > File > Browse... > [select folder] > [select files] > Camera menu > Set Exif Date to > Filename... > 'Match string' GC default: YYYY-MM-DD hh.mm.ss (or almost anything you prefer -- I use YYYY-MMDD-hhmm-ss), Additional options > Set the file creation/modification date, (optional: Set Exif date/time modified, Set Exif date/time digitized etc), Set movie tags (MOV, MP4, M4V and MTS only), Use UTC.

To copy filenames to image metadata dates can be done in exiftool:

exiftool -m -overwrite_original -ext jpg -ext heic -ext png -ext webp '-AllDates<FileName' '-FileCreateDate<FileName' '-FileModifyDate<FileName' .

To copy filenames to movie metadata dates can be done in exiftool:

exiftool -m -overwrite_original -ext mp4 -ext m4v -ext mov -wm w -api LargeFileSupport=1 -api QuickTimeUTC=1 '-AllDates<FileName' '-Track*Date<FileName' '-Media*Date<FileName' '-Keys:CreationDate<FileName' '-FileCreateDate<FileName' '-FileModifyDate<FileName' .

There are a number of user contributed AppleScripts for adding specifics into the Title files which can then be used as the file name when exporting out of the library. Some are:

• Change the Title of selected Photos to the Description/Caption - Apple Community
• Changing the Title to the Capture Date 2018
• Batch Change Title to Capture Date-Description-Padded Sequential Numbers
• Batch Change Title to Capture Date-Location-Description-Padded Sequential Number
• Script: Batch Changing the Titles to the Filenames with Extension
• Batch Changing the Titles to the Filename w/Extension

These and many other user tips can be found in the Thematic Index to Photos for Mac related User Tips 

If you just put them in Photos, they are just sorted by capture date automagically.

On a Mac I use the app Photos Workbench ($30) to add a Title to my pictures. You have lots of options-- this is what I use:

You can include the filename if you like-- lots of options.

On a Mac you can sort by the Title field, but titles don't show in iOS. But once I sort them by title, when they sync to the iPhone they're in the same order. I copy the title, without the index, to the Caption filed so the information shows up in iOS and iPadOS.

You only list Apple TV as your device. I haven't tried to edit pictures on my Apple TV.

I, too, use GraphicConverter ($40)  for this sort of thing, but I want to add the caution that you can't use GraphicConverter for pictures inside Photos! It works great if you're doing the operation before importing. If the pictures are going into Photos anyway, I like using Photos Workbench.

This may not apply to the original poster, but some pictures, like scans, don't have a capture date that represents the date represented by the picture, so sorting by date doesn't work. The date changing routines, like Photos' "Adjust Date and Time..." or those in GraphicConverter, seem awkward when dates are kind of random.

So I'm using Titles for the dates. I can just type in a date under the picture, sometimes just "1937", or maybe "1988 10 31," and sort by title. I do wish there were a way to copy the Title into the Exif capture date.