Here is the latest analysis of the spectrum of WASP-127b, led by Jessica Spake and newly announced on arXiv.
The different datasets come from the Hubble Space Telescope and the Spitzer Space Telescope. Spake et al see obvious features from sodium, potassium, water and carbon dioxide. They conclude that the planet has a super-solar metallicity and that its skies are relatively cloud-free.
WASP-127b is a highly observable target since, despite being less than Saturn’s mass, it is bloated to larger than Jupiter. The puffy atmosphere projected against the host star gives results in a strong signal observable during transit. Spake et al look forward to observing the planet with the James Webb Space Telescope, and say: “the hint of a large absorption feature around 4.5 microns is strong evidence that future observations of WASP-127b with JWST will be able to measure the abundances of carbon-bearing species in its atmosphere”.