Thanks for the post, I was able to reproduce the problem you are having. I'll log a bug for this, and as a work around, please convert the first test step that enters text into the text area to a customized step.
So using your example, the first step would look something like this in code:
Pages.SimpleForm.TestTextTextArea.Text = "keyword1";
Please modify the code so each new line you want to start will begin with "\r\n" (or each line you want to end, however you prefer to see it).
So the modified code example will be:
Pages.SimpleForm.TestTextTextArea.Text = "keyword1\r\nkeyword2\r\nkeyword3\r\n";
You would not need any further recorded steps over the text area like separate text entry test steps or Enter key press steps, just append or modify the string as above.
And should print out the following in the text area:
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items