What attracted you to the Proac speakers?
Have you seen https://meniscusaudio.com/product/er18mtm-ribbon-pair/
should sound similar to the Proac’s and what you’ll learn and the satisfaction derived could make up for the sound difference if any.
Also a fun read with some insight on what DIY entails.
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1637209185