I've been wrestling with a design problem for the Greek lowercase in this late-19th-century style art nouveau typeface, Cristoforo. The upright has been long done, and the italic is pretty nearly done... but the Greek is bothering me, so I am presumably about to revisit it in both fonts.
Stress is the angle at which the thick vs thin parts of the fonts are emphasized. Traditional Greek lowercase has a different angle of stress than Latin. The average Latin font as having a stress angle of about 30° (oldstyle) to 0° (modern), but old Greek is typically 120° in the lowercase. However, more “latin-style” Greek lowercase with latin stress angles is also common and acceptable, depending on the typeface. (Greek caps don’t get the same stress angle, though. They tend to consistently get the same stress as Latin.)
This particular typeface is a Victorian Art Nouveau thing with vertical stress in the Latin (and Cyrillic). So the Greek caps also have vertical stress. What should I do for the Greek lowercase?
Latin in the font:

Two different approaches to Greek lowercase, below—currently both are in the font. Top is traditional Greek, bottom is more latinized.

Currently, there is this odd mix. I am thinking that's a bad thing.
Comments
At that point you can start harmonizing the rest of the Greek letters the omicron. For the bottom of the rho and other straight descenders, look to the flag shapes of the E and F... they might look good turned 90 degrees. I'd join the beta bowl the the stem...I think an inner curl is a little too showy, every for such a fancy typeface.
* Except the bottom of the bowl of the g which looks like a mistake to me. Not the tail...I mean compare the bowl to the d.
I agree with Ray that the counters need to be narrowed. The "ηικμ" sequence in the second line stands out as much closer to the Latin not only because of the stress but also because of the smaller interior spaces.
I'd maybe loosen up the head serif on eta/iota/kappa, which obviously matches the Latin but feels out of character with the rest of the Greek. It's tempting to make the parts that seem most "matchable" match, but in effect that can make the more intransigent parts seem even more disagreeable.
Thoughts about going straight Latinized and making the Greek lowercase narrower make sense to me, I think.
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I’m happy for you to post my comments, I just don’t have time myself for discussion forums.
and his one later comment: “My pleasure. It’s not an easy style you’re working in…”