I am not familiar with the T62+ but as no one seems to have any suggestions for you I'll throw the following into the pot. I am assuming the device has access to the Play Store in which case you might like to look at Zoho Corporation's Notebook app
https://play.google.com/store/apps/d...notebook&hl=en.
I have been a OneNote user for many years but wanted something else just to keep simpler notes in and have them arranged in collections which most notebook type application cannot do. Notebook was suggested to me and I've found it does pretty much everything I wanted.
Its basic structure is that one creates notebooks and in those notebooks one can create notecards. So, for example, for a business or holiday trip one could create a notebook for that trip and in that notebook create a notecard for each organization or place visited in which one writes the notes relevant. It will take audio notes, attach images and other attachments and also scan documents - so during a visit one can scan into the relevant notebook anything of interest. It has an excellent checklist note editor too.
It is big, around 100MB, and while if one just wants to take text notes it seems an overkill it does do the simple stuff better than other simple note taking apps I have tried and it keeps ones notes organized in an easily accessible way.
It does not, however, store .txt files in itself, but it has very good export abilities (sends notes to email and other messaging, PDF, etc. and will import Evernote notes) and among those it will offer to export to any of the .txt editors it sees on the device so giving you a .txt file if wanted. However, I find that I rarely do that as Notebook will sync with Notebook on ones other devices and PCs over the internet so ones notes are available everywhere.
It does sync through Zoho's own servers on which ones notes remain resident as do automatic backups of earlier notes so one can revert to any of those in case of problems or for review - some don't like the idea of their information being on the servers of corporates, however Zoho is substantial enough to have offices in a number of countries and produces business, financial, etc. software, and have a comprehensive and well produced website. They offer Notebook as a freebee and it is regularly updated and maintained.
I use it syncing between my phone, tablet and PC but I don't see any reason why it would not be OK on eink displays as there is no animation.