What to do after editing the formatting in a way that makes cards more difficult?

Anki Desktop
1

For example converting sentence cards to isolated vocab cards.

If I make a formatting change like this that makes it so legacy memory data may be unreliable (for example for cards where I couldn’t read the word but was passing it off of memorizing the context), what is the “blessed” way to handle this? Do I have to just reset? I have like 1k cards full of reviews from the old format that was ineffective for me.

2

You could alternatively set the cards to be due today or over the span of a number of days. Ones you struggle to recall will naturally have their ease level go down, and the others won’t be penalized if they happen to have above-default ease levels.