Syriac is a liturgical language, and the script it is written in is not confined to liturgy. Several modern Aramaic languages are written in Syriac letters and are spoken today, principally by Assyrian, Chaldean and Syriac Orthodox communities in the Middle East and in a large diaspora.
Turoyo is one of them. It has sounds the classical alphabet was not built for, and the answer has been the same one the script has always reached for: marks added to existing letters, three dots above or below, rather than new letters. The sibilants take them often. Another modern written Aramaic uses the eastern hand with its own conventions.
This matters for how an alphabet entry should be read. The twenty-two letters are classical and fixed, and describing them says nothing about how many sounds a living language written with them has. A speaker of a modern Aramaic language reading a Syriac letter is not reading a historical curiosity, and the pronunciation they give it is theirs rather than a departure from a standard.
These are also languages under real pressure. War, displacement and dispersal have moved their speakers a long way from where they were spoken, and the communities that maintain the script are far smaller than the geographical reach of its manuscripts would suggest. The alphabet is in current use, and that use is not secure.