This has frustrated me, too, but I've found three solutions that might help.
--The first thing I did was copy the clip that I wanted to subtitle, open it in a new project, extend its length, and add the fading in and fading out text. I then exported it back to the original project, and trimmed the ends . . . which gave me the subtitle without the annoying fades. This, of course, takes many steps, and in the process I discovered Subler.
--Subler is a program (and there are many like this) that add true subtitles to projects, such as translations to movies. It looks very tedious--you have to assign which frame the subtitle starts and ends on--but if you are translating an entire film, you have to do it. You can put the titles at the top or bottom and change the color, but there's not a lot (that I saw) in changing fonts or anything like that. In effect, you put your video and a subtitle file together, and this program burns the titles onto the film.
--Then I discovered the best solution (for what I needed). Create your titles in any design program and export them with a transparent background. Simply import them into your project and use them as a overlay--either a cutaway or a picture-in-picture--and as long as the background is transparent, the titles will show over your scene.
I was very frustrated that Apple changed the ability to control the fading in and out, but I'm happy that I stumbled upon these solutions. I hope they help.