Where do you get "it" from? There is no it in the Finnish sentence. I believe it should be "There are a few flowers here already".
In this sentence "tässä" can be understood as an essive case of the word "tämä" - this. The translation does sound a bit off... a better way to express "it has a few flowers" would be "siinä on muutama kukka".
I think there are two possible translations, yours and "This already has a few flowers".
"It has a few flowers already." should also be accepted.
"It has already a few flowers" sounds right to me but is not accepted.