How can I remove glue smears and blobs from engineered hardwood?

Depoends on the glue, read the label to see what solvent the manufacturer recommends. Once you find the correct solvent then test it in a hidden area or on a scrap if you have any. Before removing with solvent I'd try a plastic putty knife at a very sharp angle to remove the bulk of it.

This is a tough one because if the adhesive has dried and cured, you can remove the glue and yet it will look like it is still there. That is because the urethane in most adhesives will actually lift or remove a thin layer of the finish from the floor. Bostik Urethane Adhesive remover works good as well as Dri-Tac Urethane Adhesive remover. I would not use a putty knife, plastic or metal without wrapping a rag around the blade of it as you could very easily scratch the finish. As a flooring contractor I have experienced the difficulty of not cleaning a floor good and then having to go back and clean dried glue off. I wish you the best. No easy answers, just a lot of elbow grease.