The command syntax help for /scoreboard teams option shows the option names capitalized but the feedback when setting an option or when no or an invalid option value is provided prints the option in lower case.
Note: If the lower case versions are intended it would be good to replace all options and values with lower case and words separated by underscores ones. Otherwise options like seefriendlyinvisibles are kind of hard to read.
- Create a scoreboard team
- Have the syntax help shown
→ You will see for example "seeFriendlyInvisibles"
- Have the syntax help for this option shown
→ You will see that the option is printed in lower case: "seefriendlyinvisibles"