Oscar Stern

https://www.electricviolinshop.com/sensicore-violin-high-a.html Good news we have this High A String for Soprano Violin so you could tune C, G, D, A (a fourth above a Standard Violin) made by Super Sensitive. It's a very light gauge string but it's coated to protect it.

You would need special Strings made for that called "D, A, E, B Quint Higher Strings". They're working on Helicore versions of those strings which are stronger.

Also w/ advanced Technology we now have Helicore strings which are thinner to help w/ bowing on the strings.

Come on, the Air will come out of the F Holes so maybe it's useful.

A digital caliper might help with measuring the Diameters of the strings in Thousandths of an inch

They're only a bit thicker but not too thick, they're just the right size to produce a good sound. Improvements in technology means better strings & better tone.

So here's the Helicore (Steel Rope Core Flatwound) Cello String set, it's for 1/8 Size cellos but it can be used on 1/10 Size Cellos too. The top 2 Strings are Wound in Titanium which is usual but here's where it gets interesting. The Bottom 2 Strings are Wound in Tungsten & Nickel, that is the outer wrap wire layer is Nickel but there's a layer of Tungsten beneath it to make the string a little denser.

Helicore Strings are my favorite because the 2 lowest strings actually have tungsten to make them feel denser.

D'addario Helicore Strings work around that issue by being made thinner & easier to bow on, they're my favorite.

Holding it like a Nyckelharpa w/ a Strap should help. I call it a "Citolin", it's a hybrid of a Citole & a Violin.

I could only play it more like a Nyckelharpa

That is neat. Steel Strings are actually Flatwound so they're easier to bow on

It's a Yamaha Sitar-Geigenwerke cause it has Buzzing bridges to make it sound more like a Dilruba (bowed Sitar).

Actually D'addario makes a High E String for 5 String Viola (from their Helicore line) which is coated in tin to protect it.

Having said that, I have replaced those Gut strings w/ Custom made Giegenwerke (aka Bowed Harpsichord) Flatwound strings cause w/ that many strings to keep in tune, Steel Flatwounds make a big difference. Also alot of information about these kinds of strings (I use Mechanical pegs on my 5 String Cello for easier tuning).