When you try to concatenate all columns of a table using || and trmming all whitespaces from all CHAR/VARCHAR fields, I noticed that anything over VARCHAR(31825) when concatenated with other columns, seems to complain of exceeding Max size.
I am not sure if the Max size is set for complete concatenated string or just for large VARCHAR field. I suspect it is set at 32000 for concatenated string.
On an ASCII character set, the Maximum size of a varchar could be 64K because of the maximum row size.
Your character set seems to be UNICODE where each character takes 2 bytes for storage...