Kasia, most of the time when I bake I go by what I: see, smell, taste, and test.
I am a newbie here on the website in that I haven’t done anything professionally, but I do bake a lot at home for family and some for friends. Right now, am making cakes and pies, (both unbaked), to put into the freezer for a wedding picnic reception. Cakes will be just the 9” round or 8” square type, family size so I am looking for extra tips and ideas for icings, ect.
But what I will tell you is that it’s very possible that the person before you in your apartment may have never used your “oven” so to speak before you moved into it.
For example, my hubby and I when we were married 30 years ago, (I am 61 now), decided to have both of our folks over for dinner at the townhouse after the honeymoon, and then after dinner open up the rest of the wedding gifts which they bought with them.
Dinner was going to be simple: a baked chicken, some vegetables, salad, iced tea, coffee, and some type of light dessert. Well, I put the chicken into the oven, (unstuffed of course), at a decent time, say like 2.5 hours at the temperature called for. It browned nicely, and smelled good.
Finally, the folks arrived, the table was set, the veggies done, and I get the chicken out to serve it and cut into it and it is STILL RAW! OMGosh!
My dad, being the smart man that he is, asks me if I know whether or not the oven has been calibrated? I said I don’t know. So he advises me to get an oven thermometer and check out the temp. I finally bought one the next day and placed it in the oven and turned up the heat and left it there for a good while. It was twenty-fives degrees off! Jeepers, creepers!
Then I asked my husband about the oven. Didn’t you ever use the oven? No.
(A side note: my father-in-law would never eat chicken. It took me a while to figure out why.
)
We had to call a techie guy to come and calibrate the oven. Needless to say I didn’t do too much baking after that because we were in the process of moving to a single family dwelling. Hope the new home owner was able to enjoy baking with a newly calibrated oven! 
BTW, I noticed this thread was started back in April. Have you gotten the oven corrected by now?