I think it is working as it should be. Your level doesn't increase and as the revelation states:
You gain the service of a faithful animal of the night.
(explains what you get from the revelation)
You can select from a bear, boar, crocodile, shark, tiger, or wolf.
(indicates a limitation of the selection you are allowed to make)
This animal functions as a druid’s animal companion, using your oracle level as your effective druid level.
(explains how the companion works and that you use your oracle level in place of druid)
This revelation isn't level based. What this revelation does is opening up the option to get a companion as if you were a druid. The companion rules still apply as normal. Meaning it is based on your level and that favored class bonus doesn't increase your active oracle level for the companion just for the revelation and as I said this one isn't level based. (seeing all this revelation does is open the door to a companion)
Now look for example at Form of the beast:
As a standard action, you can assume the form of a Small or Medium animal, as beast shape I. At 9th level, you can assume the form of a Tiny or Large animal, as beast shape II.
At 11th level, you can assume the form of a Diminutive or Huge animal or a Small or Medium magical beast, as beast shape III. At 13th level, you can assume the form of a Tiny or Large magical beast, as beast shape IV. You can use this ability once per day, but the duration is 1 hour/level. You must be at least 7th level to select this revelation.
This revelation actually alters at certain levels and this is what the favored class bonus works on. This is at least how I see what the favored class bonus is supposed to work for and I think that is also the assessment Lonewolf made.
Searching I also came along
this topic about it. Where it was reported apparently, making me guess that my above reasoning is the reason it hasn't been altered. But the only way to get an official answer will be a bug report
