I’m not sure why you are writing about this now. I don’t believe the situation has altered recently.
My discussions with Hot support about formulas are in No afterSetCellMeta event when a comment is created (1.8.1) and Formulas support . These were in December 2016, a year ago.
Up to Hot 0.25 (December 2016-ish) formulas were a feature in the Free version. They were described as “Beta”, and used Rule.js for their implementation. Cell references did not work correctly in all cases, and I did my own additional work to get them correct.
After Hot 0.25, formulas were removed from the Free version. It was announced that Rule.js would be dropped and some kind of re-implementation undertaken. We were told to await the new formulas, in the Paid version only.
A year has gone by, and as I understand it the new formulas are still in a “Beta” stage.
For my own part, I could not manage with the abandonment of formulas from a “spreadsheet” application I was committed to, and so personally I have stuck at Hot 0.25 and not taken any updates.
I believe the above summarises the situation, unless anyone corrects me.