Depending on your past strategies to handle cards both in FMP and WD, your solution may stop working when you move your servers to 19.
See Card management in Webdirect 19 for problem description and solution.
https://community.claris.com/en/s/question/0D53w000057cz4mCAA/card-management-in-webdirect-19
You mean this one?
https://community.claris.com/en/s/question/0D53w000057cz4mCAA/card-management-in-webdirect-19
I think the topic on the community will keep changing and newer items will push this one down, making it harder to find over time.
Rather than rethinking the ux and rewriting portions of existing solutions to retrofit the functionality, a quick fix can be to put a condition in your script so that it chooses a document window for Webdirect and card for fmp.
Obviously that means you are willingly not using the now working as intended card window in Webdirect.