I think you have to do the flash cards multiple times to be effective. I've manually written out 1000 hindi flash cards. I would go through them a few times each day. I usually add a few of the older cards randomly, and I've had good progress over the course of a year. I think it was better for me to use that than Anki since I had to learn to write the devegnari.

I also heard finnish is a really hard language, so maybe it's that.

How have you been making these flashcards? Finnish word in front -> English word on the back?

I have used the technique from "Fluent Forever" [1] to create my flashcards using images, not only translations for learning Swedish the past years and it works surprisingly well. Much easier to fixated words when you have a more personal connection to it, finding the right image for them is part of the process and it's worked for me, personally.

Of course, using the language and having reasons to learn a specific word help even more. I've used my deck to learn words that I came across in newspapers, in government articles and so on, to expose myself to words outside of the daily conversation usage.

Another technique from "Fluent Forever" that I think helped me a lot was listening to minimal pairs to train my ears to the sound of Swedish and intuitively know how words sound when spoken.

[1] https://blog.fluent-forever.com/simple-word-flashcards/

I'd love some flashcard with native language. For example, I'm from Finland and I've been using Anki to leard Japanese, but there's no Japanese to Finnish sets available. So, the only way to learn using Anki is to translate Japanese -> English -> Finnish. And there's often new English words for me which will need a translation. I guess this kind of double learning is effective, but sometimes a little frustrating. I have decided to write some Finnish explanations to each kanji, which takes time.

Still, I think Anki is great for remembering new words. You'll just have to use it daily.