Weather models are not very good at giving a direct temperature forecast in mountains. In particular global models but also the regional ones. This is due to their horizontal resolution and mainly to the coarse orography model that they include in their computation.
As example GFS shows these altitudes in its orography model.
This model cannot ‘’see’’ Mount Logan at its real altitude. Limited area models like NAM have generally a finer orography model. But that is not enough and in mountains the only way is to consider the temperature at different levels in free atmosphere as you do with Airgram.
In the Sounding you have posted you see that the ECMWF model considers Mount Logan at 3028m (model altitude) instead of 5858m. It cannot give the right temperature !
It would be useful that Windy shows the model altitude in Meteogram.
Meteoblue model called METEOBLUE AI has been developed in Switzerland to better integrate the altitude in mountain weather forecast. This is probably the reason why you get a better information with this model.