Well I am not a licensed mechanic, but these would be my recommendations based on my personal experiences.
With today’s fuels and electronic fuel injection there is far less need for Spark Plug changes and certainly not with 3500 km annually. Probably a good idea to check the plugs annually and give them a quick clean if necessary, but unless they are oiled up or have signs of overheating, leave them be. Cap, Rotor & Wires should last at least 50k under normal use.
One important maintenance item is to flush the brake fluid on a regular basis. Every two years at least and once a year if you track the car. Brake Fluid is hydroscopic meaning it attracts moisture and in cars that aren’t used much, the contamination builds up. Not only does this reduce the effectiveness of the brake system, but it can lead to internal corrosion. Same goes for the Clutch hydraulic system.
Timing belts should be changed every 50k or 4-5 years, whichever is the sooner. They do deteriorate just sitting there under tension and a belt change while not inexpensive, is far cheaper than a head rebuild or worse. Most people change the balance shaft belts, tensioners and water pump at the same time.
Coolant should be changed every 3 years to refresh its anti-corrosion properties.
A good Fuel Injector cleaner in the fuel tank every Spring is a good practice.