What does "Awaiting SE Preliminary Decision" mean for IEEE transactions journal?
A reasonable guess would be "section editor", that is, an editor responsible for a thematic section.
The wording suggests that there will be a further check. In some journals, there is a final check by the editor-in-chief for every article. Normally, you can expect that the outcome of this check is positive, as editor-in-chiefs are usually very busy and inclined to trust their editors.