From the screenshot that you have provided and the code that you have provided, I am a little unsure exactly of the visualization that you are looking to achieve with the Infragistics XamDataChart in Xamarin.Forms.
Looking at your screenshot, I imagine the Grey and Orange areas are your two AreaSeries instances, but then it almost looks like you are looking to have a sort of "stacked" column series at occasional intervals in your data?
From your code, it looks like you are trying to use a separate CategoryDateTimeXAxis per ColumnSeries as well, which I wouldn't really recommend. Is there a particular reason you are unable to use the one that you are using for your two AreaSeries in this case? I don't really see a reason why the CategoryDateTimeXAxis shouldn't let you plot ColumnSeries with the same X-Values but different Y's, because as long as the X-values are the same, I would expect that they should show up, and the NumericYAxis will interpret the ValueMemberPath accordingly. For example, if you placed a numeric property on the same data item that you are using for your AreaSeries elements, I would imagine you could just use that as a ValueMemberPath for your ColumnSeries and fill it out with double.NaN if you don't want a column plotted or use numeric values if you do.
It is also worth mentioning that if you use multiple CategoryDateTimeXAxes, you may wind up with a skewed view unless you set the MinimumValue and MaximumValue properties to consistent values.
One issue that you will likely have in this case is the fact that the ColumnSeries was really only designed to be used with the CategoryXAxis, and not the CategoryDateTimeXAxis. The width of the columns in a ColumnSeries really depends on how many columns will actually be plotted, and as such, if you only have a few, the columns might be very large. If they happen close to each other, they also may overlap in an undesired way. You can read further about this at the WPF thread (the XamDataChart works the same in WPF and Xamarin.Forms), here: https://www.infragistics.com/community/forums/f/ultimate-ui-for-wpf/107504/item-width-is-not-expected-in-columnseries-with-categorydatetimexaxis-on-xamdatachart.
It is also certainly possible that I am not really understanding your requirement very well in this case. If this is the case, would it be possible for you to perhaps attach a sample isolated project that may demonstrate where you are at with this issue? Again, though, using the CategoryDateTimeXAxis with the ColumnSeries in the XamDataChart is not really recommended, and so achieving a visualization like the one you have provided may prove rather difficult.
Please let me know if you have any other questions or concerns on this matter.
I have been investigating the sample project, and I can see the behavior that you are referring to. You are correct in that if you are using a CategoryXAxis or CategoryDateTimeXAxis, you need to have the same X-Axis values. As such, I would recommend that you either utilize multiple CategoryDateTimeXAxis elements for your ColumnSeries in this case, or that you normalize your ColumnSeries' data sources.
To "normalize" these data sources, you can ensure that you have the same X-values for both. You don't necessarily need to have a plotted Y-value, though, and to prevent this, you can set the value used for your ColumnSeries' ValueMemberPath to double.NaN.
There are a couple of other issues that I am seeing with the sample project you sent as well. For example, there is no MinimumValue/MaximumValue set on your CategoryDateTimeXAxis elements. This will cause the axes to fail to "sync" with the NumericXAxis that you are showing at the moment. I see that you are currently setting the MinimumValue/MaximumValue properties or your NumericXAxis to 3800 and 4500, respectively, and so I would recommend setting the Minimum and Maximum values of your CategoryDateTimeXAxis to DateTime.Today.AddDays(x), where "X" is the value that you are passing to the NumericXAxis MinimumValue/MaximumValue properties. This will sync your axes and allow your ColumnSeries to show up on top of each other when the X-Value is the same.
The final issue here is one that I mentioned above. The ColumnSeries is not designed to work with the CategoryDateTimeXAxis due to the "continuous" display nature of that axis. The ColumnSeries will determine the width of its columns in the CategoryDateTimeXAxis by the underlying number of items to be plotted. If you wish to prevent the columns from being large, you can use the double.NaN technique that I mentioned above to "pad" out your ItemsSource and cause the columns to be thinner. Still, there is no guarantee that the columns will not collide with each other.
I am attaching a modified version of the sample project you sent with the above-mentioned modifications. Note, I had to pull your code into a solution of my own as I was getting some odd XamlCTask-related error when trying to build yours. Also attached is a screenshot (named Screenshot.png) that shows the output and expected behavior of the two ColumnSeries with your AreaSeries using the CategoryDateTimeXAxis elements.