Obviously, you read between the lines. Please, read again. I’m not “The Dark One”, I just pointed out other people are having the same issue.
I know it’s a free service, but you know a service is not good when even if it’s free, you still don’t want to use it.
Thanks for the support, but I’ll move on. Good luck 
To be honest, I am very confused at this time. These are very different issues you just brought up.
I’d agree that n8n has a bit of a learning curve, but it’s a rather powerful tool, automating lots of tedious tasks. It does have it’s limits though and the specific update you are performing is one of them.
I have provided a working sample workflow that can act as a base for further experimenting and learning on your end. Whether you invest the time and effort to do so is up to you.
With expressions specifically it’s well worth reading the respective documentation section to get an understand of what you can do with them. For a more holistic understanding of n8n there’s also a free course.