I agree, this could be better, but as a workaround, you could use a beastmode formula to compare your actual vs. your target, and then use that result as a summary number.  Then you'd need to create two separate alerts (one for greater than, and another for less than).

for example...

let's say that your target is a number that already appears in your dataset called `target` and your actual number is called `revenue`.  The following formula should allow you to add to summary number.

SUM(`revenue`) - MAX(`target`)

If the target doesn't appear in your dataset and cannot be easily joined via dataflow or datafusion, you could type the target amount directly in the formula so it would look something like this where your target is 1000000:

SUM(`revenue`) - 1000000

After you save this formula and check "Add to Summary Number," save the card and then create an alert for when the summary number is less than 0 and another for when it is greater than 0.  I've actually used this type of alerting system in conjunction with the 3-color face gauge cards as a quick indicator of whether anyone needs to take action or not. 

Hope this helps!!!