[Personal opinion]TE is sort of useful for specific situations, though it would not be particularly useful for what I perceive you want. When you are using TE, ISPF messes with the data you entered. This can be a good thing for some specific situations, but unless you need it, you should not use it. Pasting data is one situation when it should
not be used.
From ISPF HELP -
TE - text enter, to format the screen for power typing one or more
text paragraphs
Now, like I said before, somewhere in PCOMM options or settings you can find the settings to copy and paste data in a block mode. After nearly 20 years I cannot tell you what to set, nor tell you the exact terminology PCOMM uses, but it is there somewhere. Your technical support should be able to find it or at least tell you where it is. Perhaps your colleagues can tell you.
[Personal opinion, again]PCOMM is one of the better 3270 terminal emulator programs, though it is rather expensive. Because of its high cost I do not use it, and have not used it for almost 20 years since a brief time as an IBM employee in 1999 and 2000.