Can align-current handle aligning a varying number of columns?

Question

I'm attempting to write a rule for align-current for Robot Framework tests. Columns are delimited by multiple spaces in a row (I know, what an awful choice) and each row can have a varying number of columns (essentially each column is a function argument). Can this be implemented with align-current?

Here's some example input:

Log  fooooooooooooooooooooooooooo 123 456
Log differently  something else  bazzzzzz

Desired output:

Log                fooooooooooooooooooooooooooo 123 456
Log differently    something else                          bazzzzzz

What I have at the moment is:

(add-to-list 'align-rules-list '(robot-mode-align-test-data
                                 (regexp  . "\\(  +\\)")
                                 (modes   . '(robot-mode))
                                 (repeat  . t)
                                 (spacing . 4))

which works except for the final column on the second line in the example above.

I've tried including \n in the align regex, but I think emacs ends up in an infinite loop (until it hits line length 256 when presumably it gives up).