Super fun idea! That syllables package might not be robust enough for this purpose. Even in its documentation's super simple code samples, it estimates the word estimate wrong haha. I think that's somewhat meant to be an admission by the author that it is an estimate.
>>> import syllables
>>> syllables.estimate('estimate')
4
Doesn't matter in the context of making a fun web app though, cool idea!
I recently wrote a static site generator from AnyBox's local database, since they currently only allow for backups via iCloud which is locked down on my work laptop. I was surprised by the peace of mind it gave me to have a nice, 100% portable version of my vast bookmark/website archives.