Even your single-put commandline is wrong, so it probably does not work correctly either. It misses one quote. It should be:

https://winscp.net/eng/docs/commandline#syntax

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If by your last sentence you mean that you want to have the commands in a file, then use /script parameter:
https://winscp.net/eng/docs/commandline#scripting

Hey
I want to schedule a transfer via Task Scheduler from one remote server to remote FTP

So far I've created a task that opens "C:\Program Files (x86)\WinSCP\WinSCP.com" with added argument: in a single line.

But as soon as I add multiple put-commands nothing works.
Ideally I want to have all my arguments on file, not inputed directly to task scheduler.