I can't see a "Sent" button in Mobile version of Electrum...
The closest thing is the Mobile version's "Send" button below the Main tab (transaction history) which shouldn't be confusing since it's next to "Receive".
If so, that "Send" button in watch-only wallet is used by Cold-Storage setup to create an unsigned raw transaction to be able to export the .psbt file/text to the signer offline wallet.
It wont be able to sign, but that's one of the process to 'Send' with that setup so the button's name should be fine.

Anyways, suggestions are also welcome if you have a better alternative,
post it as a "feature request" 'issue' or include the code changes with a 'pull request' in Electrum's GitHub repository: github.com/spesmilo/electrum
The developers may implement it if it's reasonable.