Hello,
There was a company named cortical.io that built text to sdr encoders, but IIRC they never released code open source. They used to post on this forum, you can search for them disussing their research. Ex: IRIS: New version of free Cortical.io Demo now available!
Some years ago I researched text encoding using a modified HTM. I made a video explainnng my findings and Id be happy to answer any questions about it. Video Lecture of Kropff & Treves, 2008