"Change block type" makes more sense then "Change block language". "Language" sounds like it could mean English, French, etc. whereas "block type" is unambiguous.
All blocks should be collapsable - I was playing with it and had to enter a comment marker in some to be able to get the collapse arrow in the bar, like # in a python block, however the behavior for a python block collapsing vs another - is that the python block collapses to ' ... ' Whereas, other blocks maintain the firt row as a header, so if I label another block NOTES and collapse it, I can still see the header.
So a collapse button on every block would be nice.
Maybe a block header which includes the timestamp for block birth and whatever text on that line for the title. So row 0 of every block would be the block meta header? no feature creep I promise...
Yes, I've learned that Heynote is lacking some documentation. Will improve that.
Math.js (https://mathjs.org/) powers the Math blocks, so what's supported by Math.js should be supported by Heynote, with the addition of currency conversions (exchange rates are updated daily).