I agree with @Deenuji,
Long press "A" is not functional natively in PAD. You could try another scripting language and call it from PAD.
Here is a tested PowerShell version developed by my CustomGPT - PAD Assistant:
Scripting.RunPowershellScript.RunPowershellScript Script: $'''Add-Type -AssemblyName System.Windows.Forms
[System.Windows.Forms.SendKeys]::SendWait(\"a\")
Start-Sleep -Seconds 5
[System.Windows.Forms.SendKeys]::SendWait(\"{a up}\")''' ScriptOutput=> PowershellOutput
I ran this against a blank Word document and set Focus Window on it before applying this script.
Note: when I manually hold "a" for 5 seconds in Word, I get a lot of As. This could be a behavior of Word or some interaction between Word and the keyboard to press/release repeatedly.
When I run the above script, there is only 1 "a" in my word document, so that is something to keep in mind.
Good luck,
Mike
PS: if you have a paid GPT subscription and would like access to the PAD Assistant Custom GPT, please feel free to reach out.