Everything you say is true, but we are farther along than your comment indicates.
With a 6.5 meter space telescope and a star shade, we pretty much have the capability within just a few years to blot out the direct light from the host star and perform spectral characterization of exo-Earths using the light from their host star that is bouncing off of them. In particular, this is a direct exoplanet observation, not indirect like the host-star radial velocity method. An example being studied right now is HabEx (https://en.m.wikipedia.org/wiki/Habitable_Exoplanet_Imaging_...).
From such spectra, we can use chemical and general circulation models to constrain the atmospheric composition, height, and temperature. We can investigate whether the atmosphere is in chemical equilibrium, or if there is some non-chemical process active. The paper referenced in the article actually does some of this (although this is a larger planet).
They are a "hm, that's interesting" kind of a signal. They simply mean that a simplistic chemical view of the atmosphere does not explain the observation. It could mean the presence of life, or it could mean some other unknown, inorganic process.
See for example the Viking experiments: they detected signs of life on Mars, only to be disproved later by better understanding of soil chemistry.
With a 6.5 meter space telescope and a star shade, we pretty much have the capability within just a few years to blot out the direct light from the host star and perform spectral characterization of exo-Earths using the light from their host star that is bouncing off of them. In particular, this is a direct exoplanet observation, not indirect like the host-star radial velocity method. An example being studied right now is HabEx (https://en.m.wikipedia.org/wiki/Habitable_Exoplanet_Imaging_...).
From such spectra, we can use chemical and general circulation models to constrain the atmospheric composition, height, and temperature. We can investigate whether the atmosphere is in chemical equilibrium, or if there is some non-chemical process active. The paper referenced in the article actually does some of this (although this is a larger planet).