These are many questions without enough information:

"Insane loss bug"
I read your post several times and didn't find info about a "bug" you have experienced. Can you give us more specific info on that?

"it does not fix my average prices."
What do you mean? When you use averaging, the EA shows the average price of the position at the top of the chart. Do you think it was wrong? What MT version you use. Please provide a strategy for additional tests.

"I have terrible losses because of this"
What is the connection between the averaging and the loss? What results you received on your MT backtest and on your demo test?

"Only 1 night of trade me cost me 190 usd"
We don't have idea how many positions you opened, what was your entry amount, Stop Loss... What was the Max Drawdown of the backtest? Please give us more info.

"How to fix this?"
What exactly you want to fix?

"How to 100% prevent losses when adding new lots?"
Adding lots will not produce losses. You may have loss only when close lots.

"Why is this happening?"
Many reasons are possible and we cannot answer you without additional information. Most probably: you opened too many positions, the entry amount was too high for your account, your SL was too far away, your expert trade more frequently than you expected.

Please provide your strategy and MT screenshots or logs so will be able to answer.

"2nd question:"
Second? It looks like the fifth.

"Why are your ForexSB strategies so slow when tested on MT4?"
Mhm. You probably speak for your strategy. I normally use strategies that do not require tick testing and produce equal results when use the other MT testing methods. (By the way, from where MT takes ticks?) Our goal is to make strategies that can be reliable created and tested in FSB Pro. We use MT tester to confirm the expert work for a short period of time (several entries and exits). Later we test the EA on a demo account (or on real with minimal entry) for several weeks.

"This XML takes me 5-6 hours of tick test for 1990-2016"
You must have several gigabytes long tick file. I don't know what do you expect. What is your time frame?

Check the black square three orders add and averaging only enough to profit for one of them. Waste of 160 USD that was automatically generated by your FSB

As I said I do not give trading advises, but because you think FSB has a bug, I'll tell you what is wrong.

Your strategy not only hasn't got SL, but it lacks of any kind of protection.

Please stop trading now!!!

Your strategy only adds lots. It never reduces lots. It has no closing condition other than Take Profit.

Do you expect your positions to close always at profit!

This strategy will not stop until you lose your complete account.

FSB Pro works well with MT4. There is no problem with the averaging.

...

Probably you miss the fact that FSB sets SL and TP according to the last entry. However this behaviour is equal in both the backtest and the real trading and the results must be the same.

Having that in mind, if a strategy adds to a loosing position it may close at Take Profit and the total result of the aggregate position to be negative.

Example:
Let's have TP - 100 points.
1st entry: 1 lot Long at 1.1000, TP 1.1100
let's the market go down and we make the second entry at a lower price:
2nd entry: add 1 lot at 1.9000
Now we have 2 lots open and the average position price will be 1.9500
FSB will set the TP 100 points above the  current entry price - TP = 1.9100

If now the market turns up, the position will be closes at 1.9100 and will bring us a loss of 400 points.

...

The are two problems in your expert:
1st. It lacks a protection. If you open a long position and the market goes down, there is nothing that will close your position until it reaches a Margin call.

2. You add to a loosing positions. Every time the EA adds to a loosing position the average position price is higher than the current entry (if it is a long position). This also lowers your TP. If it happens that the unfavorable market move is larger than your TP, it may appear that your TP is below the average position price.

How you can improve your strategy:
- add some sort of protection - SL, Trailing Stop...
- add a closing point that will limit the loss, Parabolic SAR, Day Closing, Week Closing....
- set the strategy to add only to winning position. This will prevent lowering of your TP

I may also suggest you to test your experts on a demo account or to use a minimal entry size in order to prevent unexpected losses. 

Please remember also that FSB is a powerful tool and it requiters experience and patience in order to bring the desired results.

Set "Winner" adding mode as it is shown on the picture above.

..

Current FSB Pro behavour is not random and it is not a result of a bug. All trading features are carefully designed and are tested many years. To be precise - 5 years design (2001 - 2006) and then 10 years exploitation on various conditions (2006 - 2016). Even the smallest effect has a special purpose and consideration.

I don't see what more I can add to that discussion.

Trade Safe!