Recent releases of Tinderbox do not parse CSV reliably, from most source that I use (including Airtable and TapForms), and personally I’ve stopped trying to import using this method. Other people of course will have different experiences.
I find it is better to pass the CSV through Excel or Numbers, copy that data, and paste it to Tinderbox. This gets good results, Tinderbox can create attributes (from table headers) that are not already present in the document, and import the data.
For concatenation, I find a stamp pretty simple to do:
$Text = $Text + "\n\n" + $Attribute_1 + "\n\n" ...