I'll post a few plants which I have in my side garden. Its on the sunny south side of the house, right outside my "develpment office".
However, it gets little or no sun in summer, as shade is provided by a garage on the East side (cuts out morning sun), a large Ash tree (cuts out midday sun), a very old Damson tree and a Rowan tree (Sorbus) which cut out late afternoon sun. The plants would be lucky to get 1 hour of sunshine at a certain time per day. Compound that with the fact that this is Ireland, so not a lot of sun at the best of time!
Those trees are all there since my dad lived here, and he passed away in 1984.
They are all deciduous. Thus, Ive purposely developed it as a spring garden to take advantage of the sun that gets through those bare branches. I have tulips, Crocus, daffodills, Primulas (vulgaris, veris and denticulata), Azaleas, Camellias, Rhodos, Japanese maples...
(I'll edit this later with more)
My dads favourite plant is STILL growing under that Rowan, about 4 ft from the base of a very thick trunk. Its a Paeonia officinalis 'Rubra Plena'. It must be 30 years old, and more.
In mid summer theres very little, so I haul pots of the common Container plants into position.
In Autumn, theres Tradescantia, Cyclamen coum, Cyclamen hederifolium, Anemone japonica (varieties) did very well this year. Also that Saxifraga, (same as yours), so Ive posted a photo with its companions:
Ajuga, Gentiana (it get a splash of late afternoon, evening sun), Alchemilla conjuncta, Fuchsia - always appears very late in the season, very late flowering - none this year!
If you really must plant something to shade your Acer 'Aureum', how about a Hydrangea?
I read that they grow in light shade, so I've planted a few lacecaps (see photo) in a very dark corner. They produce lots of foliage, and a few flowers. I think they are improving in flowering performance each year.
Ive got a Delphinium in that same dark corner, planted behind the Hydrangeas from where I sit looking out.
Theres a 3ft (1m) path alongide the garage wall and running parallel to that Ive planted climbers.
Ive selected Clematis varieties which fade in sun, and prefer to face North, and can tolerate shade (e.g. Nelly Moser)
Also Hydrangea peteolaris.
I'm certain I read once that Day Lillies (Hemerocallis) can be grown in shade. However, the RHS A-Z says:
Dry conditions and excessive shade will reduce flowering: some red and purple flowered cultivars do not tolerate heavy rainfall and very hot sun. Must try one in that plot. Mind you, if I leave them alone, they'll probably get there without my assistance. They are self seeding all over the place in their current sunny location.
Finally, I bought a woodlander plant this year which was quite unknown to me .Tricyrtis (see photo).
I'd describe it as a Plantsmans plant. Well, a man on a galloping horse would not be impressed. You'd have to get close to observe the small flowers in late summer/early autumn on top of lush green foliage.
They have the most exquisite markings!
You could also try Trillium.