I don't see any problem with starting multiple manufacturers at the same time. Inno would need to create a UI where players can create groups. You create a group and add your wished manufacturers. Then you do action on the group instead on the standalone manufacturers. As long as a manufacturer is assigned to a group and you do action on that the action will affect every item in the group.
Also,the client side logic communicates with the back-end logic. If back-end says there is not enough resource to start the production for the group then an error message appears. As it happens many other cases.
there is no issue with it from our side, the issue is coding on there side.
There is a reason we got a do all on the app (and now also browser) and the arrows on the app.
Workshops do not need any goods so you can code to start them all at once without consequences.
Factories cost coins, supplies, goods and or seeds. it looks like there is something making the code for it difficult.
Otherwise they would not have opted for arrows instead of start all when they coded that on the app. what the issue is we do not know. but there seems to be some issue they need to solve first and since they failed on the app the first time it's a big question mark if the'll ever be able to do it withing budget contraints. (everything can be fixed solved as long as you throw enough recources at it, but that does not make it a viable option)