Do details of my undergraduate title matter?
In the long term it won't matter at all. There might be a small effect in moving to your next position depending on whether you go to grad school or to industry, but after a few years no one will notice anymore. You will be responsible for your own reputation and people will look to that, not to the specific degree you earned - especially its title. 

I also studied math, but in the US. Here we have a very broad undergraduate education, studying many things beyond the major subject. At graduation I had qualified for either a BS or a BA and was given the choice. I chose BA as it seemed to me to be more "interesting". I had taken extra courses both in math and in other subjects. But it never mattered. Literally no one cared. For entry to grad school the transcript shows what I had done. 

But, you might use the opportunity to think about what you want to do for the next ten or so years. Grad school and academia, or industry.