we consider the Time Dimensions un-synchronous, yes, in other words, they have different flow rates, however, unlike before, even that flow rate has a
finite difference, or at least, an "imaginable" amount of difference. What does that mean? It basically means a difference of like "A few hours", "A few days", "A few Months", etc., extending to years, hundreds of them, and even thousands or billions. This basically means if a billion years pass in one of the Worlds (Space-Time Continuums), only a few hours, a few days, or any amount other than "a billion years" (an exact amount) would pass in the second World w.r.t the first World.
In such a case, the Time Axes between those Worlds, while not parallel or overlapping, would also not be Orthogonal to each other. However, there is indeed the fact that if those Time Axis are independent of each other in the sense of having a different direction, even if not orthogonal, then they can qualify for additional higher Dimensions, which would be needed for those time axes to extend to.
Basically, this is because you can draw as many "Lines" on top of each other in a 1-Dimensional Plane, and all those lines would still be in the same direction, even Anti-Parallel Lines would essentially be extending in the same direction, only difference being, simply in reversed flow. Therefore, they can still be represented in a 1-D plane. This is also why in cases where there's a Multiversal construct containing many Space-Time Continuums, by default, we assume that the Time Dimension of each of those Space-Times extends in the same direction, and therefore would not qualify for an additional Higher Dimension, as there's no need for such a higher Dimension to exist for those individual temporal Dimensions to extend to.
However, what if you draw 2 lines that are non-Parallel or "completely" overlapping? This results in you requiring a 2-Dimensional Plane to contain or draw those lines, because those lines, even if intersecting, must have some "Space" between them, if they are not parallel or completely overlapping. Even if one of the lines is parallel or overlapping with the X-Axis (and thus having its Y-coordinates as 0), the second line, which is not parallel or overlapping to it, must have "some" Y-Coordinates. Resultantly, 2 such lines would always require a 2-Directional plane to represent. A
graphical representation would preferably explain better, I suppose.
However,
this would not extend to the need of additional Higher Dimensions for each additional Time Axis, because while two lines having different directions need a 2-D plane to be presented, infinite such lines can also be held within the same
2-D plane. We know that Time by nature is Orthogonal to Space, therefore, a Multiverse fulfilling this case must be at least
5-D, the
3-D Space of such a Multiverse would hold the Spatial Aspects of all the Space-Time Continuums it holds, whereas the latter
2-D Plane will hold all the Time Axes of those Space-Times extending in their respective direction. Resultantly, the totality of the Hyperspace would be
5-D. Additionally, in case the Hyperspace also has an overarching Time Dimension, then the Hyper Space-Time would, in this case, be
6-D on total.