Semicolons in Russian
A lot of sentences in Duolingo have confusing comma splices and a lack of semicolons, but when there are semicolons, they’re always in the English sentences and not in the Russian sentences.
Are there no semicolons in Russian?
Yes, here is one example: Я давно собирался зайти в гости к этим людям, пригласившим меня еще месяц назад; но я все не мог решиться, и каждый раз, когда я проходил мимо их дома, я невольно ускорял шаги.
Because it is "a beginning" stage of Russian, they won't use semicolons
Semicolons are more fancy punctuation marks used in literature and very seldom in real life. And there are also no real rules about using semicolons, you can put it in any really long complex sentence and say that this is your authorial intent. Commas tho are everything in Russian, so you might want to learn how to splice your sentences with them.