Flow is a nightmare, and with heavily aquascaped tanks it is even more difficult.
Traditionally both filters would be on the same side wall pointing the same way to get a circular flow pattern, however often hardscape and plants get in the way. People then opt for the opposing side front to rear as you have to try to combat hardscape and plant barriers. This often becomes a struggle and then spraybars along the back wall are utilised to try to offer the best flow pattern and distribution to most plants in heavily compromised layouts.
With aesthetics becoming more important spraybars, filters and pipework become undesirable, so then glass lily pipes are utilised. You then have to mess with positions to achieve the best flow pattern for your tank whilst not compromising the overall transparent aesthetic.
In your case with your internal filters, you may need to move each unit towards the centre of each side wall to create an area of flow centrally that collides pushing water downwards to your dead spot. Not ideal as you do lose a bit of motion but you can eliminate dead spots. Then it becomes a choice of plant species so you can offer less demanding species to the areas of less flow etc to compensate for poor circulation......
Perhaps on reading your post again I have misenterpreted your filter position and they may be on the same side, in which case if all your plant mass is central and rear bias you may need to add spraybars to them along the rear wall or place the filters themselves on the back pane facing forwards to get the circulation to the plants.
And it goes on
