For the most part, you can use LED bulbs in place of halogen bulbs. It's done all the time, no matter what country you're in. The issue becomes how the LED bulb is made - the way the LEDs are mounted in the bulb unit.
For example, some LED bulbs have LEDs all over and around the bulb body - something like this -
The issue with these types of bulbs is that they don't mimic the original location of the halogen filament in the conventional bulb and do not properly use the reflector structure of the headlamp housing. This can cause major amounts of glare for other drivers and not focus the light output properly for you to see at night.
Other manufacturers use a bulb design that closely mimics the location of the halogen filament - like this type -
Because of this design, the light output is better "managed" by the factory reflector housing and causes less glare and focuses the light output better onto the road surface.
JTRC makes mention of the heat sink and that is another aspect of the design to consider. The LEDs generate heat, any electronic device will. Many styles of bulbs have a heat sink "outside" of the headlamp housing - and often have a cooling fan bult in that runs off the same electric that powers the LED. That's fairly common. But there are also bulbs without any type of heat dissipation and this can lead to your lights burning out quicker and even damaging your headlamp housing.
I agree with JTRC that the design is a bit ... well, odd ... and so I wonder how well they would work. Honestly, the best you can do is spend the money and buy them and see how they work. Bur be aware that you may well have to adjust the headlamps up or down to minimize the glare. When I added LEDs to my 2014 Forester, I had to re-aim the lamps to keep the extra glare and blinding of other drivers to a minimum.
Not all Forester models use the same "type" of bulb. H4 is a specific size and has a specific electrical hook up (those flat contacts from your example). Others use a different type of connection (like in the picture I provided).