Looking good, looking like Scala Sans modified?

You are right, Scala Sans has some similarities (haven't noticed this yet).

It's no modification of Scala, but was derived from Sofa Serif, which is based on a drawing of mine. But of course there are influences from post-modern typedesign Scala belongs to.
My first thought when drawing was "how would Formata Serif look like?", but I think it has left this initial thought, while working on it.

This is great - lots of feedback for you...

I know you haven't tightened spacing yet (its good loose!) but, relatively speaking is there too much space on A? E and F right sidebearings loose?

Plus (in no particular order)...

Apostrophe (quoteright) seems to be a quoteleft in pdf?

Lower arm of k seems optically thinner than upper arm? Upper case seems OK.

u (and mu) seems considerably narrower than n and h? Maybe optical?

breve light compared to other accents?

Dots on i and j too heavy? Are they same as period?

2 (and perhaps 7) looks wide compared to other numerals?

Do arms of multiply deliberately not cross at right angles?

Stroke at the top of the 1 seems inconsistent with the rest of the typeface? Tapering is a new treatment (except in accents such as grave, acute, circumflex, caron etc) I can't find another shape like it. Can't it be like other characters? Something like this (I have deliberately left the arm quite long to help with tabular numerals)...

Arms of E and F seem narrow compared with horizontals in D?

t seems very hooked compared with f and j etc?

Crossbar on T looks very straight (less organic than other 'straight' strokes, eg arms of E and L.

Acute on Lacute is drifting left? Looks right on small caps lacute.

Bar on Tbar drifting left? Looks right on small caps tbar.

Dotaccent is lower on characters than dieresis? Both are lower than dot on i. Would the position of the dot accent be governed by the dot on either the i or the dieresis... it's neither.

Numerators and denominators look small? Also the 1 (numerator, denominator, superscript and subscript) looks very bold compared to other numerators (and you already know my thoughts on the 1).

Questionmark (?) seems to be falling over to the right at the top. Same with inverted question but bottom left.

Beautiful work!

Thanks a lot for this detailed feedback, Nick.
That motivates me to go on right when I have the time to do so, but for now... I have to sleep (3am here now, forgot time while working on a Antiqua variation).
I'll have a closer look and give a more detailed and adequate answer tomorrow, but for short: I think you are right in almost every point.

sebilar

Nick, sorry for my late answer.
I've found out that I first have to finish Sofa Serif before I can work on with sans, as there are too many cross-links between the two fonts. If I change one detail in the first one, I have to do it in the second one too. This ends in madness...

But I could make use of a lot of your comments on Sofa Serif as well, as they are applicable on the general design, not only on one part of the family. You can see some of my changes based on your comments on V25 of Sofa Serif already. I've left out the ones concerning Diacritics, as they change and shift too often at the moment. I'll do them right when finishing the font.

Thanks a lot for that,
sebilar