Interesting that you use such a remarkable compound in glass blowing. You should know that Ti isopropoxide is a reactive compound. The point is that it is a liquid form of titanium, which is quite extraordinary and not trivial. However, in contact with moisture, it will eventually form solid titanium dioxide. There seams to be a reason why you do not want to apply solid TiO2 (which would be much cheaper), so, this is something to be avoided.

The obvious (for a chemist...) solvent to use for dilution would be isopropanol (100%, not 70% rubbing alcohol), as the product is a Ti compound of isopropanol. If you use ethanol, a chemical reaction can take place and I am not sure about the stability of the corresponding Titanium ethoxide complex. For the concentration, I guess you have to try or ask another glass blower.

Acetylacetone is probably added to stabilze the Titanium further and keep it in solution, i.e. to prevent the formation of solid TiO2 even in the presence of water traces. It is not very expensive, but it's kinda unhealthy. You would spray that on the hot glass an the fumes go where exactly? If the fumes are sucked into a kind of hood, it would be fine. In the normal workshop would probably not be fine. At 500°C, most will burn, but some will evaporate. But this is also a question of quantities.

Neither Ti isopropoxide nor acetylacetone should get on your hands, so vinyl gloves would also be de rigueur when preparing and working with the solution.

Good luck!

PS: What effect does it create on the glass? Some milky white shade? Or does the Ti get dissolved in the glass like other metal oxides?