This is an issue that could make your internal configuration project so easy or hard. If you determine it as a bearing wall, it means you don’t need an engineer site visit and will save time and money. Where you want to remove internal walls or add in new door and windows, your concern is very genuine about the structural members and what could happen to the roof above, Don’t worry, just raise the part of the plywood from the floor above or plasterboard from the ceiling and take a look at the direction and place of the joists of seating.

bearing wall and partition wall

If the end of the joists sits on the questioned wall, it means that the wall is a bearing wall and need a structural calculation for the new beam. But if the joists are parallel to the wall or they continue over the wall, it means the wall is a partition wall and you can knock out the wall without any concern.
For the first condition found out that the specified wall is bearing wall, you can specify the measuring of the removed wall and send to the engineer and ask for calculation for the single beam.