When creating a custom tech tree and changing the description of a tech it effects the core race tree also. They have the new name in their tree.
excerpt from custom TechDefs.xml
<Tech>
<InternalName>BarocianInstitutionalResearch</InternalName>
<GenericName>InstitutionalResearch</GenericName>
<DisplayName>BarocianInstitutionalResearch_Name</DisplayName>
<TechTree>Barocian_Tree</TechTree>
<ShortDescription>BarocianInstitutionalResearch_ShortDec</ShortDescription>
<Description>BarocianInstitutionalResearch_Dec</Description>
<ColorDef>TechCyan</ColorDef>
<Icon>GC3_Engineering_Tech_Icon.png</Icon>
<Bink>GC3_Research_Temp.bk2</Bink>
<ResearchCost>88</ResearchCost>
<TechPoints>1</TechPoints>
<AICategoryWeight>
<Military>20</Military>
<Growth>16</Growth>
<Tech>22</Tech>
<Diplomacy>8</Diplomacy>
<Expansion>16</Expansion>
<Wealth>10</Wealth>
<Influence>12</Influence>
<Fortification>14</Fortification>
</AICategoryWeight>
<Prerequ>
<Techs>
<Option>Infiltration</Option>
</Techs>
<TechAge>
<Option>AgeOfExpansion</Option>
</TechAge>
</Prerequ>
</Tech>
excerpt from custom TechDefsText.xml
<StringTable>
<Label>BarocianInstitutionalResearch_Name</Label>
<String>XXX Rename Test</String>
</StringTable>
<StringTable>
<Label>BarocianInstitutionalResearch_ShortDec</Label>
<String>Allows construction of improved research facilities.</String>
</StringTable>
<StringTable>
<Label>BarocianInstitutionalResearch_Dec</Label>
<String>We're at our best when we're not just living in this universe, but observing it. Figuring it out. Sometimes dismantling small parts of it. By setting up special places for that to happen, we expect research breakthroughs to occur much more frequently.</String>
</StringTable>
Renaming Institutional research as above will have the name 'XXX Rename Test' in the core races trade screen.
Didn't notice this prior to 1.9.
Edit:
Not a Bug, just me not paying attention.