Yes, your interpretation is correct. I hadn't considered the possibility of it being interpreted that way. Thank you for pointing it out.

This kind of notation is often used in other language versions. For example, "set(action)" is rendered as "placer (set)" in the French version and "legen (set)" in the German version (there is no space before the left bracket in the Japanese version, but there is in the German and French versions). However, I found only a few such examples in the English version, so I can see your point.
/magiaauto [subcommand]
[...]
>>Subcommands:
　attack (atk)
I believe confusion is unlikely since there is a separate explanation for the example:
>>Examples:
　/hotbar action "Mount Roulette" 1 1
　(Places Mount Roulette in slot [#1] on hotbar [#1].)
However, I have no strong preference regarding listing both subcommands in this manner, so I’m happy to leave it to the l10n team's decision.