I would assume that the signature is a template.
Yes, quite probably, but on our vases they show enough differences to indicate different templates. But an alternative, at least for my cameo piece, is that the signature part of the cameo was worked by hand as part of the acid mask prior to dipping in the acid.
Interesting that the opal glass on the inside of your vase is like the opal on the outside of mine, and that the finishing of the top edge does look similar.
The mouth shape of our vases does have similar lines. See below for more photos of mine, which also show the mottled effect of backlighting.Mouth shape - top view
This shows the oval form - quite sensous!!Side view showing curved form
Also "sensous" in its own way.Mottled effect with backlighting
Here, the mottled yellow / brown glass gives a very nice summer or autumnal effect - in my opinion.
The size of the vase is 18.5 cm (7 1/4 inch) tall, 16.5 cm (6 1/2 inch) wide and 9.5 cm (3 3/4 inch) deep at the base narrowing to 6.7 cm (2 5/8 inch) at the mouth. It weights in at 1.47 Kg (3 lb 4 oz)
The inner layer is a thick clear glass with a thin yellow + brown (or is it a dark green?) mottling. This is covered again with clear and then a layer of brown. The brown layer has been etched partially through to reveal the design of plants and dragonflies and etched fully to reveal the yellow & brown seen through the clear layer.
It's all very good work. But I have never thought the addition of the 3D dragonfly body (which is also acid etched) with its bulbous green eyes to be an attractive feature.