You’re using wrong function name or wrong parameter type.
There is no such function as app.vault.adapter.modify, and the vault methods (app.vault.xxx) expects TFile instead of a string path.
Just take a look at the Obsidian API docs, it has comprehensive list of available methods and corresponding parameter types:
app.vault.<METHOD>: Vault - Developer Documentationapp.vault.adapter<METHOD>:DataAdapter - Developer Documentation
Use Vault if possible. (The only scenarios where you should use adapter that I can come up with are when dealing with hidden files, files in hidden folders such as .obsidian)