Bitcoin Core is the gold bitcoin standard for reliable Bitcoin software. It is written (primarily) in C++. Programmers such as gmaxwell, sipa, and others who write excellent code for this project have no need to switch to another language, unless they find technical reasons which would make another language a better tool for the job. Also, they have no need to be taught certain practiceswhatever they do, it is evidently working.
Yes this is a great code (not speaking about underlying mathematics).
Funny that on this board exists the thread
https://bitcointalk.org/index.php?topic=2990217.0 started by the person who could not read the code of bitcoind.