Specify the size of a font in a fontset, but let it be scaled by `text-scale-adjust`

Question

I want to use Inconsolata LGC's Greek with Inconsolata (plain Inconsolata has better hinting than Inconsolata LGC). I've set up a fontset (of course these are things you copy from Stack Exchange)

(create-fontset-from-fontset-spec
 (font-xlfd-name (font-spec :registry "fontset-inconsolata")))
(set-fontset-font "fontset-inconsolata" nil "Inconsolata")
(set-fontset-font "fontset-inconsolata" 'greek "Inconsolata LGC")

applied it to my Inconsolata face,

(defface Inconsolata
  '((t :family "Inconsolata" :height 120))
  "Inconsolata face.")

(set-face-attribute 'Inconsolata nil :fontset "fontset-inconsolata")

and now Greek displays allright. Almost. The problem is that Inconsolata LGR is larger than Inconsolata, so the text looks like this

I can specify the font size for Inconsolata LGC in several ways, e.g.

(set-fontset-font "fontset-inconsolata" 'greek "Inconsolata LGC-10")

or

(set-fontset-font "fontset-inconsolata" 'greek (font-spec :family "Inconsolata LGC" :size 10.0))

so then the Greek font's size is right

but all the methods I've tried make it deaf to text-scale-adjust:

So how can I set the size of the Greek font and make it heed text-scale-adjust?

---

Full output of C-u C-x =, on e:

             position: 14 of 247 (5%), column: 1
            character: e (displayed as e) (codepoint 101, #o145, #x65)
              charset: ascii (ASCII (ISO646 IRV))
code point in charset: 0x65
               script: latin
               syntax: w    which means: word
             category: .:Base, L:Strong L2R, a:ASCII, l:Latin, r:Roman
             to input: type "C-x 8 RET 65" or "C-x 8 RET LATIN SMALL LETTER E"
          buffer code: #x65
            file code: #x65 (encoded by coding system utf-8-unix)
              display: by this font (glyph code):
    ftcrhb:-CYRE-Inconsolata-normal-normal-normal-*-19-*-*-*-m-0-iso10646-1 (#x112)

Character code properties: customize what to show
  name: LATIN SMALL LETTER E
  general-category: Ll (Letter, Lowercase)
  decomposition: (101) ('e')

There is an overlay here:
 From 13 to 16
  face                 hl-line
  priority             -50
  window               #<window 3 on rotational_energies_and_heat_capacities.jl>


There are text properties here:
  fontified            t

and ε

             position: 13 of 247 (5%), column: 0
            character: ε (displayed as ε) (codepoint 949, #o1665, #x3b5)
              charset: unicode (Unicode (ISO10646))
code point in charset: 0x03B5
               script: greek
               syntax: w    which means: word
             category: .:Base, G:2-byte Greek, L:Strong L2R, c:Chinese, g:Greek, h:Korean, j:Japanese
             to input: type "C-x 8 RET 3b5" or "C-x 8 RET GREEK SMALL LETTER EPSILON"
          buffer code: #xCE #xB5
            file code: #xCE #xB5 (encoded by coding system utf-8-unix)
              display: by this font (glyph code):
    ftcrhb:-PfEd-Inconsolata LGC-normal-normal-normal-*-16-*-*-*-m-0-iso10646-1 (#x185)

Character code properties: customize what to show
  name: GREEK SMALL LETTER EPSILON
  general-category: Ll (Letter, Lowercase)
  decomposition: (949) ('ε')

There is an overlay here:
 From 13 to 16
  face                 hl-line
  priority             -50
  window               #<window 3 on rotational_energies_and_heat_capacities.jl>


There are text properties here:
  fontified            t

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