Its possible the flex line was fitted when the blue oil hose mod was installed due to components clashing. If your engine is a certified red label version, without required mod cert approval, it is no longer certified.
Unless there is a log entry the high pressure fuel flex line should be regarded as an unknown, and unless it can be identified as a high pressure fuel line then it would be prudent to replace it with a verified known spec component.
Just because it looks right does not always mean it is. The last aircraft I purchased, after having a bit of a poke around, I realised the previous owner should not ever been allowed near any tools; which motivated giving the aircraft an entire and thorough scrutiny and expunging of all remaining badness.
If the aircraft is 24 registered then return it to factory spec and maintain your insurance cover.