Steps to reproduce:

Set the system region format to one whose decimal separator is a comma and whose group separator is a dot, for example Region: Germany with any language (System Settings > General > Language & Region)
Start the Editor and open the attached project. The Editor reads the region format once at startup, so it has to be started after step 1
In the Project window, right-click Assets/Doc.uxml and select Reimport. The attribute is parsed during import, so the asset has to be imported while this region format is active
Double-click Assets/Doc.uxml to open it in UI Builder
Select "subject" in the Hierarchy and look at the Curve and Gradient fields at the bottom of the Inspector's Attributes section
Click the Curve field to open the Curve editor and read the keyframe times and values

Actual result: the attribute values are read into different numbers than the ones in the .uxml, with no error and no warning. The curve is authored with keys at times 0, 0.25, 1 and values 0, 0.5, 1.75, and reads back as:

curve   times=[0 1 25]   values=[0 175 5]
grad    colorKeys=[0 1]   alphaKeys=[0/1 1/5]

Expected result: the same numbers that are in the file, in every region format, as under en-US:

curve   times=[0 0.25 1]   values=[0 0.5 1.75]
grad    colorKeys=[0 0.35] alphaKeys=[0/1 1/0.5]

Reproducible with versions: 7000.0.0a5

Not reproducible with versions: 6000.0.0f1, 6000.0.84f1, 6000.3.24f1, 6000.6.3f1, 6000.7.0b2, 7000.0.0a1 (macOS only: before 7.0 the Editor reports en-US regardless of the system region format, so these are platform-specific and not evidence the defect is absent.

Tested on (OS): macOS 26.0, Apple silicon