Hello,
As technical support failed to address the issues iv found and their response is a "line of code", maybe posting here, somebody will figure it out and guide me further, as a normal user, not skilled programmer and since I'm fed with technical support short answers, where it seems they don't understand the issues for payed products. 


1. If I activate e-commerce, and a user post item for sale with stock and shipping method and another user wants to buy he gets an error that City is not completed.
In Backoffice , at City field there is a Select box ( dropdown ) with nothing selected.
In front office, in user profile, there is a text box. If the user types his city and saves, nothing happens in backend.
If i set the City field manually from Backoffice everything works.
 The error persist.  I don't know if is osclass related , theme related or pay plugin related.

2. If a user has an order, and sets the status of the order from Front office to : Cancelled, Shipped etc., the status doesn't change.
 2.1 If i set the order from preparing to shipped , or confirmed, from Front office , automatically it's set as Cancelled in Backoffice.
 2.2 If i set Confirmed, Shipped, Cancelled from Back office, the status doesn't update in front office.
 2.3 The user gets an email , with Confirmed order. In the email also it states that the order is Cancelled. Payment is done via Stripe or Admin Pay.
In any of the cases, the email arrives on time, stating the order is Processing, then in the body of the email it states Cancelled
As seen in picture, the first part of the email states : Order in Processing ( underlined with red ) then START_ANNULAT , stating order is Cancelled ( underlined with red ) , and that the money are refunded. The amount is not refunded ( gladly the expenses are supported by us , using our cards , and our products so no damage here )


Tnks in advance
 

1. Address, city and one phone must be filled
2. In case of order that consist from products from multiple sellers, each seller change order status for their part only.
Status of whole order is then evaluated.
If you see issue there, can you reproduce it on demo?
3. Do bot translate keywords / magic words in curly brackets

 
1.I will and come back with screenshot.
 I agree with you that it must be filled. As I said , filling it by writing the city in the city box , does not work.
2. 1 seller , test seller ..I can't go live until every aspect is working.
3. Translation is not an issue. The cancellation is.

@StefanGr
1. If you look into t_user table, then s_city, s_address and one of s_phone_land/s_phone_mobile must be filled. This could be managed in plugin settings as well, but does not make sense to me to change it. Originally there was also s_zip, but realized some themes does not use it.
2. Ideally if you could replicate issue on our demo site or somewhere we can have FTP access.
Basically there is order status and order item status. Order item status is updated by seller (for all items at same time).
Order status is then calculated based on order item status.
If all order item status are changed from processing to shipped, order status get auto-updated to shipped etc. If one order item is cancelled, whole order is going to be cancelled (I hope so).
3. if you translate anything that is in {}, it will not work. Those are magic words being replaced or used in plugin, but after changing keywords, plugin will not know about change.
{START_ANULAT} will definitely not be recognized by plugin what is that.