In Greek the situation is a bit arbitrary. In earlier times, personal names were usually "Hellenised" not translated per se. So, we have historically, Δαρεῖος (Darius) for Dārayavaʰuš, Ξέρξης (Χerxes) for Xšayār̥šā, Nαβουχοδονόσωρ (Νebuchadnezzar) for Nabû-kudurri-uṣur, Ὀκταβιανός Αὔγουστος (Octavius Augustus), Ἰούλιος Καῖσαρ (Julius Ceasar), Μᾶρκος Ἀντώνιος (Mark Antony), Λούκιος Ταρκύνιος (Lucius Tarquinius), Τορκουεμάδας (Torquemada), Πεπῖνος ὁ Βραχύς (Pepin the Short), Μωάμεθ ὁ Πορθητής (Mehmed the Conqueror), Φερδινάνδος καὶ Ἰσαβέλλα (Ferdinand and Isabella), Χριστόφορος Κολόμβος (Christopher Columbus), Βενιαμίν Φραγκλίνος (Benjamin Franklin), Ἰσαάκ Νεύτων (Isaac Newton), etc.
Lately (as of the last 30 or 40 years), foreign names are left as they are, and the spelling is as simple and as phonetic/phonemic as possible (we avoid Hellenising names anymore); so, the French President Emmanuel Macron is simply transliterated as Εμμανουέλ Μακρόν, and not Hellenised to Ἐμμανουήλ Μακρόνιος (as he would have been 100-150 years ago), the name of the POTUS (incumbent) is Τζο Μπάιντεν, and not Ἰωσήφ Βάιδεν, Czar Vlad is mostly Βλαντιμίρ Πούτιν and occasionally Βλαδίμηρος Πούτιν.
For toponymics, the situation is equally complicated. Names of places made known at an earlier stage of the language, were Hellenised and followed the rules of declension of the Greek language: Paris was Παρίσιοι (masc. nom. pl.) and was declined accordingly=nom: οἱ Παρίσιοι, gen: τῶν Παρισίων, dat: τοῖς Παρισίοις, acc: τούς Παρισίους, London was Λονδίνον (neut. nom. sing.)= nom: τὸ Λονδίνον, gen: τοῦ Λονδίνου, dat: τῷ Λονδίνῳ, acc: τὸ Λονδίνον, Stockholm was Στοκχόλμη (fem. nom. sing.)=nom: ἡ Στοκχόλμη, gen: τῆς Στοκχόλμης, dat: τῇ Στοκχόλμῃ, acc: τήν Στοκχόλμην, Μanchester was Μαγχεστρία (fem. nom. sing.)=nom: ἡ Μαγχεστρία, gen: τῆς Μαγχεστρίας, dat: τῇ Μαγχεστρίᾳ, acc: τήν Μαγχεστρίαν, Tübingen (with the widely acclaimed university) was Τυβίγγη (fem. nom. sing.)=nom: ἡ Τυβίγγη, gen: τῆς Τυβίγγης, dat: τῇ Τυβίγγῃ, acc: τήν Τυβίγγην, Washington was Βασιγκτώνη (fem. nom. sing.)=nom: ἡ Βασιγκτώνη, gen: τῆς Βασιγκτώνης, dat: τῇ Βασιγκτώνῃ, acc: τήν Βασιγκτώνην, New York was Nέα Ὑόρκη (fem. nom. sing.)=nom: ἡ Νέα Ὑόρκη, gen: τῆς Νέας Ὑόρκης, dat: τῇ Νέᾳ Ὑόρκῃ, acc: τήν Νέαν Ὑόρκην, etc.
Nowadays, place-names are transcribed as simple as possible (with the exception of standardised names, the Katharevousian Λονδίνον stubbornly remains Λονδίνο, as do Νέα Υόρκη, Στοκχόλμη) and former archaisms are now similar phonetically and phonemically to the original (Μαγχεστρία is now Μάντσεστερ, Τυβίγγη is Τύμπιγκεν, Nέα Ἰερσέη is Nιού Τζέρσεϊ).
In Russian, the name of the northern city is actually Архангельск, not *Архангел (which is, well Archangel). So you should spell it Arkhangelsk (but who knows how you will butcher "kh", since most English natives don't know how to correctly pronounce this name)..
We call it Αρχάγγελος which is the Greek tranlation of the Russian name (Archangel).