Downgrading from 10.9.5 to 10.9.4
First of all, what you downloaded was only the service pack and not a full installation of 10.9.4. This means that you have no means of installing it directly. That said, even if you do manage to get 10.9.4 installed, you will not be able to migrate your profile from your Time Machine backup because the Migration Assistant can only migrate from older or equal OS versions. Which means you can go laterally or from older to newer, but not from newer to older.

If you have an up-to-10.9.4-specific Time Machine backup that you've archived, you may be able to use that to do a complete system restore, including your profile and applications, but you would then be looking at the likelihood of losing changes to your profile in the meantime. It may be possible to manually copy things to mitigate the damage, but I'm not sure how successful that would be.

You will probably get more mileage out of asking questions on how to fix problems that were brought about by installing 10.9.5 rather than try to revert to 10.9.4. YMMV, of course, but that would be my approach.