Этот код AppleScript работает для меня, используя последнюю версию macOS Catalina
if application "System Preferences" is running then ¬
do shell script "killall 'System Preferences'"
repeat until application "System Preferences" is not running
delay 0.1
end repeat
tell application "System Preferences"
reveal anchor "Seeing_Display" of ¬
pane id "com.apple.preference.universalaccess"
end tell
tell application "System Events"
repeat until exists of checkbox "Reduce motion" of tab group 1 of ¬
group 1 of window "Accessibility" of application process "System Preferences"
delay 0.1
end repeat
click checkbox "Reduce motion" of tab group 1 of ¬
group 1 of window "Accessibility" of application process "System Preferences"
end tell
tell application "System Preferences" to quit