Yes, that's totally correct! The current version of the plugin supports only so called "offline" HTR, which operates on images. This is ultimately determined by the underlying machine learning model.

I have developed another model however (based on a somewhat recent Google paper by Carbune et al. 2020), that operates on pen dynamics and thereby implements online HTR, see here:

https://github.com/PellelNitram/OnlineHTR

This model is open-source as well and will be part of the HTR system for Xournal++ in the future. Feel free to give it a try yourself locally.

One question that has been bothering me a long time and prevented online HTR so far for me is how to find text on a page in temporal domain (i.e. in online domain and not offline domain). If you have any ideas on that, please do let me know as I would greatly appreciate that! One possible way is a transformer model - but again that feels a bit overkill and introduces a context length.