Some thoughts (completely disregard anything at odds with your preference
)
Potamogeton gayi - for me this plant seems to prefer 20-30cm height & creeping horizontally rather than growing any taller/higher
Limnophila hippuridoides - you may find that the base leaves deteriorate over time so plan for base camouflage
the growing tips are very good at attaining height
Nymphoides hydrophylla 'Taiwan' - nice plant, I plant the "babies" in the fore or mid ground to establish as plants, then move on
Helanthium 'Quadricostatus' - this plant can show nutrition lack through transparent leaves
Sagittaria subulata - this plant loves to confound by growing taller or shorter apparently at whim
Java Fern = I'd look for a smaller microsorum species if you hope to keep this at mid-height, I like to trim this regularly rather than letting it get out of control & then doing a major trim
Anubias barteri 'Coffeefolia' - I'd tend to place this mid-ground as the leaves are quite large & it seems to like to add some height, try A barteri 'nana' if you want more of a traditional foreground look
Anubias barteri var. angustifolia - I don't see this listed much in scapes but it's really a lovely plant & provides a nice leaf contrast in texture & color
Foreground - I'd add in some grasses or Marsilea to provide texture & "fill" in case of crypt "melt" - I've had stunning crypt foregrounds melt completely (after a normal water change) when our water does it's "spring change" (reservoirs that are rain & snow melt dependent) - if your tap is more consistent, you're less likely to experience such drastic "melt"
You don't mention lighting, but I'd use HOT5 with reflectors despite this being "low tech" - tank is 50cm deep & substrate PAR is going to be low - moderate (once plants are established & growing, you can always decrease lighting) - especially if starting with 1=2=Grow plants, I like to fertilize lightly from Day 2 or 3 & run lights ~5h
I only extend light hours once plants have established roots & completely transitioned to submerse growth