Update, I just got it to work with a very ugly hack: Just add the backslash to the name of the command as well 
(I want to use this in templates with Command in space-lua to set page attributes):
```template
| Page | Stars |
| ---- | ----- |
{{#each {page where stars>=0}}}
|{{name}}| {{stars}} {[Page: Set Attribute\|Add Star]({"attribute": "stars","change":1, "page":"{{name}}" })}|
{{/each}}
```
```space-lua
command.define {
name = "Page: Set Attribute\\",
run = function(a)
system.invoke_command("Page: Set Attribute",a)
end
}
```
Turns into
The Add Star button triggers the command Page: Set Attribute\\ (need to escape \ itself in lua 
), which calls Page: Set Attribute and the 
is added. 
Bonus: Side effect of using a template is that clicking the button does not enter edit mode but triggers it right away!
Messing with the command name like that feels very wrong (and pollutes the command pallete), but it gets the job done for now.