Hi Brian, the tail is something different.

It is definitely meeting at a good angle, not at all similar to that other problem.

It looks like what happened there is that you didn't quite push the tail through the body quite far enough for it to punch all the way through, here is a view down into the inside of that section:



Notice that area looks like it did not fully punch through the outside surface:



I think that one would probably fillet fine if those parts got pushed a little bit more in when they were booleaned so they fully punched through the outer skin instead of only partially, although there is not very much room left there until it runs into the fillet on the vertical part.

- Michael