I wouldn't be so worried about it in the near future, but I would plan on fixing it eventually.
Yes, the oil is likely to run hotter than normal, if you use the car hard - if you use the car gently, it won't. Remember the car is designed to cope with all cases - including driving hard in very hot countries.
If it is hot in Bulgaria, use a heavier oil - that will fix the viscosity issues. Rather than 10W-40, use 10W-60 - this will tolerate far higher temperatures and retain viscosity. In the winter (cold in Bulgaria I think), go back to 10W-40.
Don't use cheap oil. Use decent synthetic.
When you do fix it, I'm pretty sure a standard Mocal kit, including the sandwich plate will be less than fiddling with Alfa parts.