There is no way to adjust the leading or paragraph spacing in a Premiere Elements title. But you can fudge it in a couple of ways:
1) Add a line of blank text between two lines of text. It need only include a couple of spacebar spaces. Then select that blank text line and change its font size to whatever size you need to give you the proper spacing. Or
2) Just create a separate text box on your title by clicking with the text tool. A title can include as many blocks of text as you'd like. Drag and position them as near or as far from each other as you need.
One thing that helps me determine how my spacing looks is to toggle in and out of the Edit mode.
A. For moving on the screen, use the 'Arrow' icon.
B. Going back and forth between edit and non-edit you can see where everything is. You can see clearly that Line 3 is slightly out of alignment, but in the Edit mode (See Image A) it can be more different to tell.