Potential Error in ShipBluePrintDefs.XML

I have a "local mod", where I changed those values from "Frigate" to "Cruiser" and it did help with the Ship Designer where "Cutting Principle" now appears at the root and no longer nested under "Immovable Stream".

Considering these were Battleship-level blueprints, "Frigate" does not look like it would be the correct ShipGroup.

"Cutting Principle" is considered a Frigate.  But associating that with the previous Battleship blueprints resulted in it becoming incorrectly nested under "Immovable Stream".

One thing that is very confusing and inconsistent within the web of XML files is how "Destroyer" is characterized.

In the classic sense, the following would be typical of naval vessel sizes:

Corvette < Frigate < Destroyer < Cruiser < Battleship < Dreadnought

which is a bit contrary to how they are listed, in implied size order at the bottom of ShipDesignPresetCategoryDefs.xml

Frigate < Corvette < Cruiser < Destroyer < Battleship < Dreadnought

but lets not worry about that at the moment....

A bigger puzzle arises in the XML files where some places use the Destroyer moniker when referring to "Medium Sized" ships, whereas others "Large Sized" ships.

As in the previous example in ShipBlueprintDefs.xml (with the suspected incorrect "Frigate" ShipGroup attribute):

<ShipBlueprint>
    <InternalName>DestroyerBlueprint</InternalName>
    <ShipDesignPresetCategory>Battleship</ShipDesignPresetCategory> (defined in ShipDesignPresetCategoryDef.xml )
    <ShipHullType>Large</ShipHullType>
    <Role>Capital</Role>
    <ShipGroup>Frigate</ShipGroup>

However, in ShipDesignPresetCategoryDefs.xml, there is a "Destroyer" category defined as a Medium-sized ship:

<ShipDesignPresetCategory>
    <InternalName>PresetCategoryDef_Destroyer</InternalName>
    <DisplayName>PresetCategory_Destroyer_Name</DisplayName>
    <Description>PresetCategory_Destroyer_Dec</Description>
    <SpecsDescription>NEW_DESIGN_SPECS_LABEL_Destroyer</SpecsDescription>
    <BenefitsDescription>NEW_DESIGN_BENEFITS_LABEL_Destroyer</BenefitsDescription>
    <UniqueID>Destroyer</UniqueID>
    <DefaultShipHull>Medium</DefaultShipHull>

But in ShipClassText.xml and ShipClassDefs.xml we have entries like the following that use the "Immovable Stream" name for the Altarian Destroyer.  However, "Immovable Stream" is a Battleship, not a Destroyer.       

    <StringTable>
        <Label>AltarianDestroyer_Name</Label>
        <String>Immovable Stream</String>
    </StringTable>

  <ShipClass>
    <InternalName>AltarianDestroyer</InternalName>
    <DisplayName>AltarianDestroyer_Name</DisplayName>
    <Description>TerranAllianceDestroyer_Dec</Description>
    <ThumbnailOverride>Altarian_Destroyer_01T.png</ThumbnailOverride>
    <ShipHullType>Large</ShipHullType>
    <ShipRule>FavorMissile</ShipRule>
    <ShipDesign>Altarian_Destroyer_01T</ShipDesign>
    <AIShipClass>Battleship</AIShipClass>
    <StrategicIcon>Destroyer</StrategicIcon>
    <BlueprintDef>DestroyerBlueprint</BlueprintDef>
  </ShipClass>

Currently, it is extremely difficult to assess the design intent for "Destroyer" type ships. (Medium or Large?)

There are clues that this may be a recent new category of ship, which, IMO, does not appear to be fully fleshed out.