You can do this nicely with Titler Pro, you find it in the text menus under New Blue.
Drag the Titler down to your timeline and place it under where you want your text to show. Stretch it as necessary.
Enter your text as you wish, Then under the library tab select shapes and then click on "rectangle" to open the selection. Try as an example dragging down the Bar Grey Fade and place it under the text in the New Blue Titler timeline. Click on the attributes tab and then select "object" and reduce the opacity to about 30%.
Make sure that in the titler preview screen that the bar is behind your text. Also make sure that on the titler timeline the text is above the shape. If not you can drag it to the correct place.
So what you should get is text with a background that's not affected by your video colours
Panny TM10, GH2, GH4,