The picture helps. It appears that everything is functioning normally. Perhaps your book does not offer quite as much detailed, specific info as it could. Although I can't blame the author...the book would be a billion pages long if it explained every last tiny detail.
Join - describes the condition of wall intersections that exist (and other things oustide the scope of your complaint) but of course does not automatically extend/trim them to create an intersection.
Trim/Extend - causes the length of walls (and some other elements outside the scope of your complaint) to change in order to create intersectins.
Clean-up - relates to intersections in regards to the layers of walls (and some other elements outside the scope of your complaint) flowing together without a break when they should.
Now lets think about the offset tool. If you have a pair of walls intersecting at 45-degrees as you have, and you offset one of them, the length of the new wall will match the original. Revit cannot know whether you want it to also trim/extend, or in which direction (if you had three walls in a chain for example). If you offset both of the walls to the same side, during one use of the trim/extend tool, only then it will auto-trim or auto-extend (depending on which side you offset to) both of the new walls to create a new intersection appropriately offset from the original.
The Create Similar tool basically just turns on the appropriate tool (the Wall tool in this case) and pre-selects the same type. So functionally, it allows you the exact same click-to-place operation as you would expect if you just used the Wall tool to draw the walls. It does not magically know that you want the new wall trimmed or extended. If you want it to create a new intersection, you'll have to start or end or cross the new wall at/with another wall.
The clean-up appears to be working fine in every intersection shown in your picture. Each like layer is flowing through each intersection in the way that should be expected by default.
