Issue
The information is legible in 2160 × 1440 (16:9 landscape):
However, it’s not whatsoever easily readable when small:
and would be significantly worse if constrained to 16:9 portrait.
Solution
A simple solution would be line numbers.
However, at that point, I expect that you might as well use something like the KWrite KPart (with modifiability disabled) so that you don’t need to reimplement it.
That basically describes the Konsole KPart, but I don’t know whether Line numbers in Konsole applies to its KPart.