The issue is not with the Helical Insight application but with the database itself. You are trying to rename columns which include capital letters. You can make the same name with all small case letters and it will work fine. Like in your example: “cost of travel”
The same thing is happening when you do a custom column, the capital case letters are not supported by redshift, unless you explicitly make those settings on database server level.
Including some references from DB provider (Amazon) that might help you further:
You need to set property SET enable_case_sensitive_identifier TO true; at database server level so that it becomes case sensitive and then you can give any kind of alias name but if you don’t set this property globally at server level then you have to give all small cases names to your custom column or column alias.