As the clipping in your first post makes clear, Standard Flex designations correspond (roughly) to full load displacements. (And note that SF 3000 - not 2000 - is the designation associated with the 3,500 tonne Thetis class.) It is also important to remember that StanFlex numbers were effectively marketing designations - eg: note that KDM stopped referring to SF 300 (or, sometimes, a hyphenated SF-300) once the Flyvefisken class were officially named.
I've seen no evidence of SF numbers for 'early adopters' of Standard Flex modules - MLU mods for the 1,450 tonne Niels Juel class corvettes and one-off 1,970 tonne Beskytteren class Inspektionsskib. Still, it would make sense that StanFlex designations would have been at least briefly applied to Odense's 1,720 tonne Knud Rasmussen class Inspektionsfartøjer; 6,300 tonne Absalon class (Kommandostøtteskib; and 6,645 tonne Iver Huitfeldt class FFH.
A bit more background on the SF 1500 for those who aren't familiar ... this was an early '90s project led by Danyard Aalborg A/S (simply Danyard A/S then) backed up by Anglo-French BAeSEMA (as it sounds, a joint venture between BAe and the Sema Group).
Danyard's SF 1500 project was based directly on the hull design of the Niels Juel class. That steel hull was to be combined with a composite superstructure constructed mainly from FRP sandwich panels (based on SF 300 experience). At an early sage, the SF 1500 was to have 5 x StanFlex modules (not the 6 listed in your source).
By 1992, Danyard and Odense Lindø were grouped (along with Terma and others) within Naval Team Denmark (NTD) which emphasized the export potential of Standard Flex. NTD then proposed SF 1500 to meet Malaysia's New Generation Patrol Vessel (NGPV) programme in the early 1990s. This was followed by sales junkets to Brunei and Thailand (the latter having also shown interest in the SF 300 for MCM).
Source (including attached image): Naval Team Denamrk organisation og virksomhed (NTD organisation and company), kommandør Arne Stihøj Pedersen, in Tidsskrift for Søvæsen, Nr.1 - 2004 - 175. årgang