I must admit this will probably work, you could join that extra strip on and reinforce it with the new bubble trap, and it will probably hold for a good while if you clean the glass and silicone it well.
Your work looks good on the other seams so I believe you would be successful, but I must ask......Why not replace that entire baffle with a taller one and then add the bubble trap in?
It means re-doing work you have already done, which is painful for sure, but think about looking in on this sump in a year or two, will you be happy to see how you solved this issue? given that (IMO) you dont necessarily NEED to rush some sort of a repair at this point.
Were it my tank I would pull the entire baffle, clean it up, and replace with a taller one, and add the bubble trap how you have it shown.
but you could totally just glue that extra strip in and as long as you clean and clamp it the silicone should keep it from going anywhere once its cured.
I felt the same way when I realized that it wouldnt work like this and thought I'd have to pull out that baffle to replace it with something taller. I realized that even if I removed it and put in a taller piece that the water would still slowly creep over that corner into the return section from the skimmer section. I think the only way it works 100% the way I want is by having the new strip hang over into the fuge area just a bit. (or atleast over the top of the other baffle)