There is a lot of hate on SB for the Cloud in general, and the Shearwater Cloud program specifically. But the latter may just be a misunderstanding...
When you upload from your Teric/Perdix to the device you are using (iOS, Android, Windows, whatever) it is ONLY going to that device, not to the "cloud." Your data NEVER goes to the "cloud" unless you tell the program to send it. So you can log away to your heart's content, without ever invoking or needing the "cloud."
However, suppose you want to update your firmware in your Teric/Perdix; then you have to go get the new firmware from Shearwater and go through the update process...which is what the Shearwater Cloud app on your devices does for you. So far, it is functionally like the old Shearwater desktop....your Teric/Perdix speaks only to your device, and your device goes and gets any new firmware you need. What the Shearwater Cloud app (iOS, Android, Desktop) does in addition is allows you to store your data on Shearwater's servers (the "cloud") and synchronize it between devices.....if you want; you do not have to do this. So, on a dive trip, I can upload my Teric to my phone, when I get back on the internet I can sync my phone to the "cloud," and when I get home I can sync my desktop to the "cloud," and there is my dive data.