two problems with terminator: vi and line spacing/cursor size

[Marco Fioretti]

Greetings,
I need help with two separate problems with Gnome-Terminator, because I am honestly out of terms to search for
PROBLEM 1: these days, as I said in another thread here, I am doing some experiments that require the highest possible resolution in text terminals, even when running in GUI mode:
https://lists.ubuntu.com/archives/ubuntu-users/2023-May/310313.html (https://lists.ubuntu.com/archives/ubuntu-users/2023-May/310313.html)
While playing with those settings under both wayland and x.org, I messed something up because now the text cursor is twice as high as before, and indeed the space between consecutive lines in Terminator is double than before. That is, an "ls -l" listing of ten files now is twice as "tall" as it was before I started messing with resolution inside terminals
Other terminals (I tried xterm and konsole) do NOT have the same problem.
What happened, and how do I go back to the original setting?
PROBLEM 2, with vi: (this has ALWAYS happened on my desktop, on every terminal, I just had no time to report it before)
At the prompt of a LOCAL shell inside, I type "vi somefile", then "i", then "hello world". So far so good, the file look as it should, 1 line (X is where the cursor is, in vi insert mode):
line 1: hello worldX
If I press the left arrow key, 
line 1: D
line 2: hello world
that is, pressing that key ADDS an extra line above the starting one, with a capital D inside.  What on Earth happens here, and how to fix it?
thanks,
Marco
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