I think you're looking for something like this :
CN179 Pluggable Terminal Block | Brimal Components (bclstore.co.uk)https://www.bclstore.co.uk/product-page/cn179-pluggable-terminal-block
Have you considered this one:
https://www.ebay.co.uk/itm/EDDIE-STOBART-DOOSAN-DAEWOO-MEGA-300-V-W054-1-76-New-Boxed/143856087142?epid=1648576316&hash=item217e7db066:g:eVUAAOSwkcBa73XZ
Have you looked at the DCC Concepts SS Surface mounted point motors ? - their control board has built in frog polarity.
https://www.rmweb.co.uk/community/index.php?/topic/160481-a-surface-mounted-point-motor-with-built-in-frog-polarity-switch/&tab=comments#comment-4230532
Malc
I also have one listing all my locos, their addresses and function button operations and another one listing all the LED lighting by switch number and relevant wiring colours for fault finding.