Resolved Error 200 - Undefined array key 1 on line 220 preventing proper import

I have a rather complex set of csv data to import into content items with custom fields (using Tasos Custom Fields extension).

When I try to import the data, it starts importing and then after a few seconds I get:

An error has occurred during the import. Below the information received from the server.

Status error: 200
Status message: parsererror

Warning: Undefined array key 1 in /var/www/vhosts/.../plugins/csviext/joomlacustomfields/PlgCsviextJoomlacustomfields.php on line 220

The entries do get imported in to Joomla. They appear properly in the articles list. They appear to properly import the fields: title, alias, Date created, and category for all of the pieces.
Some of the pieces import properly but others do not.
However, when I try to open some of the imported articles (on the admin side) I get::

An error has occurred.
htmlspecialchars(): Arguent #1 ($string) must be of type string, array given
(see the callstack details in the attached file)



If I just try to import a few of the fields I don't get this (the import works properly - even when using a few custom fields); however, trying to remove field by field and re-testing is way too long to try to figure this out.

I'm attaching
- the template XML file
- the csv import file
- the latest log file
- callstack.txt file (when trying to view an article that had issues)

We're running:
RO CSVI: 9.2.0
Joomla: 5.4.0
PHP: 8.2.29
DB: MariaDB/11.1.6

I've been unable to find any good documentation or other support requests that match this error or provide any explanation why/where the undefined array key might be.

Please help me understand why this error is happening and how to avoid it so that we can get the hundreds of records migrated into Joomla articles, which is why we purchased RO CSVI.