Hi Bartosz,
That’s an interesting problem. Normally, if we were using a Text Shape to define all characters, then we could easily apply a Bend Deformer (or some operator) to all characters. In this case, since each character is a model, we will have to coordinate the deformation across the children.
I don’t have a clean answer off the top of my head. Maybe try combining a Bend Deformers & a Stretch operator.
If you can get it working w/out configuration (i.e. just the 3D side), I can probably help you figure out how to hook it up to the configurator.