It is best to screw in the E27 socket as large a lamp. Can still be a balloon with 20cm diameter. When the light source is too small, my a cross to the ceiling by the frame. A larger bulb lamp is better illuminated. The outlines of a spiral ESL can be seen from the outside. We have a 15W bulb with 15cm diameter. That looks good. (You can buy cheap at Hornbach (FLAIR) with 5 years warranty, is as far as I know the only hardware store of an ESL store brand has) A 3.5W LED is dark.
The pity is that the animals do not like colors. Pink Giraffe, blue elephant, blue monkey, yellow Koala. Should not have been. But the Frben on the product images match the original colors.