Q: Can Tibia Coins be transferred using this application?
A: No. In general, it's not possible to perform actions with Tibia Coins via the app.
Source: Official CM reply
The reason being why is because it's not the apps current intention and security is paramount.
"Also, we want to emphasise that Tibia Observer's purpose is to inform players about certain activities or events in Tibia through notifications on their mobile devices. It is explicitly not designed to allow the performing of ingame or website actions such as buying and selling items or bidding on auctions, for example."
Source: Sep 22 2021 - Sneak Peek: Tibia Observer