It wouldn't surprise me if an acid product would mar the finish on titanium. As I recall titanium is chemically reactive, but forms a protective oxide finish (that's what aluminum does). Aluminum can be etched by hydrochloric acid. I've even milled aluminum with hydrochloric acid or with sodium hydroxide.
To remove an organic material like an adhesive from metal you usually don't want to use an acid. The acid is very likely to eat through your metal faster than it eats through the organic coating. To remove organics it is best to use organic solvents or heat and a sharp edge. If there are no plastics in the area, you can soak a rag in something like acetone, carb. cleaner (xylene) or lacquer thinner and wrap your part for a while. The adhesive (even epoxy) should get soft enough to remove with a razor blade and some fine steel wool. If there is plastic nearby that you want to protect use a little heat from a cigarette lighter, soldering iron, or torch (carefully) to get the adhesive up to over 170-degrees F. Then quickly use razor blade and steel wool. I've removed epoxy and other industrial adhesives with these approaches.
A classic mistake I made once was to try and clean an aluminum baking pan using oven cleaner. The pan had baked-on grease patches that I wanted to remove. The oven cleaner had lye (sodium hydroxide) in it. The grease came off, but the pan ended up with the pattern of the grease left in a reverse-etched pattern in the surface. The lye etched about 10 thousanths of an inch into the surface in the areas not protected by grease.
So remember, acids primarily attack metals or inorganic compounds like hard water stains. Organic solvents attack organics like glue and plastics. Detergents attack both, but a lot slower. If you can clean something with a detergent it will remove more types of dirt with less tendency to damage your substrate. Water is best.
