The important thing for plants is not whether there is or is not standing water; saturation of the soil is much more important in determining which plants will grow well. When soil is saturated the pores are all full of water, not air, which makes the diffusion of oxygen into the soil much slower. Most plant roots get the oxygen they need for respiration from the soil, and in saturated soil the oxygen supply is very slowly replaced so it gets used up by both plants and soil microbes, so as a result many types of plants suffocate in saturated soil. We usually think they drowned because of too much water, but really they suffocate because of too little oxygen at the roots. Wetland plants can transfer oxygen from the leaves to the roots, allowing them to survive in saturated soil.
Standing water is a clear indication that the soil below is saturated, but standing water isn't necessary to have saturated soil and wetland conditions, and your bog sounds like it has saturated soil.

That being said, a facultative wetland plant is one that in nature grows both in wetlands (saturated soils) and outside of wetlands, so facultative wetland plants should be able to grow in a bog, assuming other factors are OK such as pH (true bogs are usually very acidic, but your backyard bog may not be). I am not familiar with the term 'wet mesic' perennials but my guess is that it describes plants that like moist, but not saturated soil, and that a wet mesic perennial might not do well in a bog.