The .com key won't work this way as it shares a keycode with another key (which might be a bug).  You need a unique locator for the .com key, like so:

`_dotcom_key_locator = (By.CSS_SELECTOR, ".keyboard-row button[data-compositekey='.com']")`

and then, in `tap_com`, get the element using that locator and tap on it. That should work.