I have been experiencing something similar!!
In my scenario I have believed it was related to Coda automatically changing the type of a column (see this post) because what is happening is a relation column in a ‘helper’ table (therefore there is only ever one row in the table) is being changed to a text column, which is what causes the “unexpected dot operator” error. Manually changing the column back to a relation fixes it.
In more detail -
I have a customers table, and a “send email” helper table with a “recipient” column that is a relation to the customers table.
Thus I can click a “send email” button in the customers table and a row is added to the helper table, the recipient column in the helper table is set to the customer (ie. "thisRow), and the new row is opened. But for some reason, which I have presumed to be related to the column “auto-typing” that coda does (
) the recipient column in the helper table gets automatically changed to a text column, meaning there is no reference back to the customer and so the send email button which has a reference to “Recipient.Email Address” shows the “unexpected dot operator” error.
Ironically, I got around the problem by setting the value of the recipient column to “thisRow.CustomerName.ToText()” which causes the column to match the text to a customer, and doesn’t auto-type the column to Text!! 
Hopefully the above helps you in some way.