Ollie

From what we know my 1st step would be to create a stable supply via a pure sine inverter running from battery purely for the control system with the electronics. Low power unit. This would be the 240V AC that you mentioned. A cheaper solution would be to provide 230V AC from a voltage stabiliser. I guess both these units need not be more than 1.5kW but this is a very wild estimate. Measurements need to be taken to confirm power rating. This area will be more prone to fluctuations based on my limited exposure to them. The main AC motors should not give any hiccups. 
Just my view based on what is mentioned without actually measuring or seeing the type of problems on the unit. 
 

You can contact Manie on [email protected] as he sells the complete Pi with Software & cable.
It is already pre configured, so just get the cable for the Battery, Which I believe he can assist with as well

I like the "SMOKE" breaker in your last pick. Please post a video when you switch that one to ON  

That already tells me that these were used with 16 cell LiFePO4 batteries. 
The 56V is a give away as lead acids would have had lower charge voltages. 
If you get 16S Lithium batteries then you only need to change the Battery Test Termination Voltage to 46V (44V is a bit low) and then it should work well. 
Pylontech (and I think Freedomwon as well) are 16S or the batteries from LithiumBatteriesSA should work. Or build your own  

Pylontech is 15s. FreedomWON is 16s.

If you can set the charge voltages to custom values, then yes.
Inverters tend to be able to handle a fairly wide voltage range on the DC side (batteries) as the State Of Charge changes the Voltages changes as well (especially in Lead Acids), so that is normally not a problem.
The problem comes that Lithium batteries charge at higher voltages than Lead Acids, so you need to be able set those charge outputs. 

She may or may not have said that, I wouldn’t know. She’s currently on my ignore list since said incident. I felt a little hurt when she didn’t rush to help me, but rather burst out in fits of laughter.