(Is there a way to add a Subscription and set the end date manually after I import the members into Ultimate Member for UM-Switcher?)

Nope there is no option for that available in um-switcher. You can use a plugin to import users with meta, but the renewal date will not be included inside um-switcher. For this to work a programmer is needed to create a connection between your current plugin and um-switcher, not an easy task I’m afraid.

The only way I see is a massive job, well it depends of how many users there are. When you have a limited amount, you could create for your users an order via woo commerce. And for every client you need to adjust the end date on purchase. This way your users will have the end date they had before. But like I said, it’s a hell of a job….

How many users do you have?

350 users adding manual will always be cheaper then creating an extension that will import your users and also add the end date of your current plugin that handles the subscription time into a format that um-switcher understands.

(This seems like a feature that should be integrated in the future?)
Well there is no option for that built in Ultimate member, and I don’t think this is a feature for um-switcher as we designed um-switcher for a specific purpose.

Yes we offer all custom services and we can import your users for you, please send me a mail via sales@theme-dutch.com and I will come back with a quote. Please include an admin account for me so I can have a quick look at your current plugin and do my research.

I can not open your google doc, but maybe you can send it also with your email.

Regarding your question (Or a way to manually add the renewal date after I import the list?)
I will discuss this on Monday with our developer if there is way, not a bad idea!