Are there some short versions of f in Junicode or EB Garamond?
By "short" version of f, I assume you mean "short-armed" version. Please advise if this interpretation is incorrect.
I am not aware of Junicode providing short-arm versions of the f and ff glyphs. I am aware, though, of such glyphs for both EB Garamond and Libertinus Serif, in both the upright and italic font shapes.

Judging by this screenshot, I'd say that the short-armed versions of f and ff, in both upright and italic font shapes, are very well done in EB Garamond. In particular, they are immediately suitable for use in ligature-suppression exercises involving fl and ffl.
The same cannot be said, unfortunately, for the Libertinus Serif versions of the short-armed f and ff glyphs. In particular, the arm of the short-armed version of ff, in the upright font shape, is barely shorter than the arm of the regular version of ff. Hence, if the point of this exercise is to suppress the ffl ligature in favor of ff-l, the short-armed version of ff of Libertinus Serif does not constitute a meaningful improvement over the standard version of the glyph.
\documentclass{article}
\usepackage{fontspec}
\begin{document}
\setmainfont{EB Garamond}
EB Garamond:
f \symbol{983911} ff \symbol{983904}
\quad
{\itshape f \symbol{983072}\ ff \symbol{983066}}
\smallskip
höflich höf\kern0ptlich hö\symbol{983911}lich
trefflich treff\kern0ptlich tre\symbol{983904}lich
\smallskip
{\itshape höflich höf\kern0ptlich hö\symbol{983072}lich
trefflich treff\kern0ptlich tre\symbol{983066}lich}
\bigskip
\setmainfont{Libertinus Serif}
Libertinus Serif:
f \symbol{983264} ff \symbol{983265}
\quad
{\itshape f \symbol{983268}\ ff \symbol{983269}}
\smallskip
höflich höf\kern0ptlich hö\symbol{983264}lich
trefflich treff\kern0ptlich tre\symbol{983265}lich
\smallskip
{\itshape höflich höf\kern0ptlich hö\symbol{983268}lich
trefflich treff\kern0ptlich tre\symbol{983269}lich}
\end{document}
fthat I write with\symbol{983911}globally? There has to be a simple trick to this to write a short line of code in the preamble but I have not found anything that does what I want. – Nemgathos Jul 31 '19 at 22:49EB Garamondfont, and present your wish list to him? – Mico Aug 01 '19 at 09:03fandffglyphs. – Mico Aug 08 '19 at 08:59