I'm sorry to say this post will be somewhat wishy-washy - no definite answers.
I'm going to call the section of the flowers with a very different colour from the rest of the flower a sector.
A flower may have a sector because of a genetic difference or it may have a sector because of a non-genetic or environmental difference.
As one example of a possible environmental difference, sometimes a flower does not open properly and part of a petal is stuck in a sepal all day. Sometimes, if one then pulls the petal out of the sepal one sees a sector of darker colour versus the rest of the petal's colour. The colour in the rest of the petal was affected (perhaps somewhat 'bleached') by sunlight. The part of the petal that was enclosed in the sepal did not experience as much sunlight (it was shaded) and kept its colour. Something similar can be seen if one picks a bud the night before that it is about to open and lets it open in complete darkness and then looks at it. Or if one places the unopened bud in the refrigerator and lets it open. The petal colours will not be the same as those on a flower in the garden after the sun has risen [there won't be any sectors, the flower will not be the same colour indoors [without light or in the cool and without light] as outdoors in sunlight.
A genetic difference would create a genetic chimera. Genetic differences are very rare, say one in a million. However, if we have a genetic difference in a flower then that flower will not necessarily breed exactly the same as the other flowers on the plant. That depends on where the sector occurs, how large it is and in which tissue of the flower it is.
Let's assume that the sector in 'Electric City Spring Fling' is genetic (it may not be). It is large and affects one petal and one sepal. That means whatever happened did so very early in the development of the flower. In a daylily flower there are six stamens with pollen; three are 'attached' to sepals and three are 'attached' to petals. There will be one stamen attached to the sectored petal and one stamen attached to the sectored sepal. It is likely that if there was some pigment on the stalk (filament) of those stamens that we would see a sector on the stalks on the same side (half) as on the petal or sepal. It would be likely that the sectors extended into the part of the stamens where pollen is made (anther).
So now we could reasonably safely assume that there was genetic change in the anther. But we are not finished yet. There are basically three layers of tissues in the flower parts. An upper layer (epidermal), middle layer (mesophyll) and bottom layer (epidermal) similar to the upper layer. In many plant species pollen develops only from the middle layer. But in daylilies some pollen also develops from the upper and/or lower layers. The estimate of how much pollen develops from those locations varies from about 1/7th to about 3/10ths. That will probably be different for every flower and every anther.
We would need to know whether the sectors are in the upper layer, the middle layer or the lower layer or some combinations of all these. The pigment/colour that is is missing is only normally present in the upper and lower layers so we can tell that the sector is present in the upper layer. If it is also present in the lower layer then it is probably also present (we assume) in the middle layer (even though the middle layer never produces the pigment). If the sector is present in all three layers and involves half the petal, and half the anther then half the pollen in that anther will carry the genetic difference (that is, that pollen will have lost the ability to produce the pigment). If the sector is not present in the middle layer then 1/2 X 1/7 or 1/14th of the pollen to 1/2 X 3/10 or 3/20ths of the pollen will carry the genetic difference (or in this case lost the ability to make the pigment). A geneticist would produce as many hundreds of seedlings as possible from the two sectored anthers looking for that new mutation. Or using 21st century methods, pieces of the sector would be tissue cultured to grow whole new plants showing the genetic change.
