FJ Software

Yes - see Command line parameters for MyPhoneExplorer

In answer to your subject, the end result of your scripting needs to be like

d:\Path\MyPhoneExplorer.EXE action=sendmessage savetosent=1 number=123-456-7890 text="SMS message goes here"

MPE on Windows should be "connected" to MPE on Android at the time, for best results.

Not sure how this ...

So I'm not clear: does this bug "come with ... Android" or does it come from a non-"old version of MPE"?

Self-resurrecting call logs are a new problem.
Dropping back to MPE 1.8.11 with Android 6 did not fix it.
Changing Android is not realistic.
Would an earlier APK help?

This requirement is one of a very few things that all softwares must include so as to provide the minimum basic level of accessibility. It is likely already part of Microsoft's guidelines to qualify for compatibility with Windows. So yes please go ahead and remove any architectural barriers, so that ...