An enriched substrate is not necessary, and it can cause serious issues for fish. My tanks all have a regular dark-toned play sand, and the plants thrive.
Your problem in the photos is primarily the imbalance of light/nutrients generally, though there may be some need for a nutrient additive. The black rim is a form of black beard/brush algae (there is more than one form of this, and I have battled them a few times). The yellowing of the older outer (on sword plants) leaves is normal when the plant is growing as it puts its energy into the new leaves (which arise from the inside of the crown of the plant) and they have the ability to transfer nutrients from the older outer leaves which then gradually die off.
Swords are heavy feeders, and substrate tabs do wonders for them. For ten years now I have been using Seachem's Flourish Tabs, with one tab inserted close to the crown of each plant and replaced every 3-4 months. I have never had issues like cloudy water with this brand. The API tabs have been known to cause issues, but not Seachem's. And the nutrients do not leech into the upper water column, which is better for fish and helps prevent problem algae.
On the algae, we need to know the data for the tank lighting (type, watts, spectrum, duration...) and if any plant additives (like liquid fertilizer) are being used. The aim is to keep "problem" algae in check, and once the balance is established this will occur.