Acid etching of float glass
Alkaline etching of glass tends to be less rapid than HF and leaves a smoother surface. This may not be what you do for the first etch on fresh glass, but it may smooth out the etch somewhat after an HF etch. The smoothing may also be caused by silicate ions that form in the alkaline etch fluid, so perhaps a solution of potassium (or sodium) silicate (ortho or meta) would be gentler. A polysilicate might be too slow.