The majority of electrical problems are down to 2 issues. Owners and mechanics. People buy them as cheap runabouts to replace things like Corsas and Fiestas, they ARE NOT replacements for those cars. The A2 was built at a financial loss to Audi and in general only quality parts were used - yes we know about the exceptions. A testament to this is the number still on the road today. These owners used the wrong fuel, use cheapest parts only when they absolutely had to and cut servicing. Then we come to the "mechanics" who bodge, use incorrect tools, cut up wiring to fit whatever or to stop an error or warning light. As the majority of cars now have had MANY owners the neglect and bodges get compounded by each subsequent owner.
There are 3 types of A2...
1 The ones on bungee cords to the Audi dealership, GOOD garages and experienced home mechanics / owners.
2 The ones that have now passed through the ownership of those people that appreciate really what the A2 is and have now restored the car back to how Audi intended, or even better.
3 All the other A2s out there, until either the first or second has occurred. In many cases it can take a couple of years to achieve 1 or 2 above.
Most issues can be fixed, but there are some that are just uneconomical to repair. Even in those cases many parts can be salvaged to help keep other cars in condition 1 or 2 above.
Research any potential purchase, have it PROPERLY scanned with VCDS, check its history, be prepared for expected and unexpected bills. The end of the day YOU make the choice to buy it or not.