@Stevelim as you have figured Advanced XML is deprecated, so what you can try is to use Area Chart with Static Thresholds to mark ranges on chart (with light colors for obvious reasons) and then use Chart overlay to depict the required series. This option would however require you to mark Chart range color for background from 0 value onward (not directly something in the middle). I have used Lower Threshold as Light Green color and Upper Threshold as Light Red color.
Following is a run anywhere example which also uses the feature of Legends seriesCompare which is available in Splunk 7.x versions. This allows simpler selection and display of all series values. I have also used some CSS override to show Series values in Legend for Series Compare as more visible Bold and Black color.
<dashboard>
<label>Chart with Area</label>
<row>
<panel>
<html depends="$alwaysHideCSSPanel$">
<style>
#chartAreaWithOverlay g.highcharts-legend-item tspan:nth-child(2){
font-weight:bold !important;
fill:black !important;
}
</style>
</html>
<chart id="chartAreaWithOverlay">
<search>
<query>index="_introspection" data.pct_memory=*
| timechart max(data.pct_memory) as max_memory_pct by data.process
| eval lower_threshold=5, upper_threshold=10</query>
<earliest>-24h@h</earliest>
<latest>now</latest>
<sampleRatio>1</sampleRatio>
</search>
<option name="charting.axisLabelsX.majorLabelStyle.overflowMode">ellipsisNone</option>
<option name="charting.axisLabelsX.majorLabelStyle.rotation">0</option>
<option name="charting.axisTitleX.visibility">visible</option>
<option name="charting.axisTitleY.visibility">visible</option>
<option name="charting.axisTitleY2.visibility">visible</option>
<option name="charting.axisX.abbreviation">none</option>
<option name="charting.axisX.scale">linear</option>
<option name="charting.axisY.abbreviation">none</option>
<option name="charting.axisY.scale">linear</option>
<option name="charting.axisY2.abbreviation">none</option>
<option name="charting.axisY2.enabled">1</option>
<option name="charting.axisY2.scale">inherit</option>
<option name="charting.chart">area</option>
<option name="charting.chart.bubbleMaximumSize">50</option>
<option name="charting.chart.bubbleMinimumSize">10</option>
<option name="charting.chart.bubbleSizeBy">area</option>
<option name="charting.chart.nullValueMode">zero</option>
<option name="charting.chart.overlayFields">mongod,python,splunk-regmon,splunk-optimize,splunkd</option>
<option name="charting.chart.showDataLabels">none</option>
<option name="charting.chart.sliceCollapsingThreshold">0.01</option>
<option name="charting.chart.stackMode">default</option>
<option name="charting.chart.style">shiny</option>
<option name="charting.drilldown">none</option>
<option name="charting.fieldColors">{"lower_threshold":"0x90EE90","upper_threshold":"0xFF7F50"}</option>
<option name="charting.layout.splitSeries">0</option>
<option name="charting.layout.splitSeries.allowIndependentYRanges">0</option>
<option name="charting.legend.labelStyle.overflowMode">ellipsisMiddle</option>
<option name="charting.legend.mode">seriesCompare</option>
<option name="charting.legend.placement">right</option>
<option name="charting.lineWidth">2</option>
<option name="trellis.enabled">0</option>
<option name="trellis.scales.shared">1</option>
<option name="trellis.size">medium</option>
</chart>
</panel>
</row>
</dashboard>
