When adding a boolean expression to an Automation, e.g. a==b. If you go to the properties and try to change the data type for the two variables from Double (default) to String, you get an error "InvalidExpression" in the Design Area. I've tried to Clean Solution and Rebuild with no luck. (see attachment: invalid_expression.png)
What I found works is to select "Identifiers - String" by right click in the Boolean Expression in the local variables of the automation. (see attachment: identifiers_string.png)
Probably not a fancy workaround but it took me a while to figure it out how to continue the automation by doing this. It might save some time for anyone experiencing this issue.
I was unable to reproduce your issue, but certainly, using the hyperlinks on the properties window or the options on the context menu like you suggested is how I would normally edit the identifiers anyway as that is much faster and easier.