Have you tried just writing one or more INSERT statements in the query tool? In that way you won't need a CSV file and can just type them in the text area as opposed to the data grid.
I wanted to input some 10 tuples into a simple table. I thought I could do that in a spreadsheet-like GUI as in MS SQL Management Studio, but the UI of PGAdmin was a lot more inconvenient. I looked around and found that it has an "import data" feature. CSV was good-enough but it required the CSV to be a file. Can't pgAdmin have a textarea that allows users to type or paste CSV directly without using a file? I mean, creating a temporary CSV file and selecting the file in pgAdmin was not that convenient because pgAdmin's file browser dialogue is not as good as the OS native version.