firstly, a very, very newcomer to this space, and don't have any knowledge of its operation at all.
When we lack experience and knowledge, we are easy to trick. Be very very careful. Don't rely on one person to explain this. Especially not a stranger you have never met.
I have been corresponding with individuals regarding recovery of scammed funds
I would ignore anyone who contacts me privately over Facebook or other social media private messaging.
You'll get better advice if you keep all communications in a public place like this website where many people are reading the questions and will quickly correct any misleading answers.
I've been told I need to pay 0.19258 BTC to activate the transaction
This usually means someone is trying to steal more money from you. You don't need to pay any kind of activation fee in any normal kind of Bitcoin transaction.
In this situation I would forget about any "scammed funds". They either never really existed or are under the control of a scammer. Usually there is no realistic prospect of recovering control over this money. I would think it prudent to discontinue use of any wallet that was ever under the control of the original scammer or subsequent "helper".
I have the details of the hash, which lists 18 different transactions
That's probably a Bitcoin address. That doesn't give you control over money, it just lets you see some transactions associated with that address. The address does not identify a person, business or place. Knowing an address doesn't give control over any money.
a total of 4.35 BTC. Can I send this to my account?
I sure hope the answer is ýes'
Unfortunately scammers are very good at exploiting hope. They are very convincing. I would stop communicating with them - no good can come of prolonging contact with criminals.