Learn English – A preposition for “act”

One phrase that's often used is bring to life (or come to life).

There's a famous Christmas song that uses this wording:

Frosty the Snowman, is a fairytale, they say.
He was made of snow, but the children know he came to life one day.

There must have been some magic in that old silk hat they found
For when they placed it on his head, he began to dance around!

The phrase is also used (albeit as a pun) in this headline:

Bringing Frankenstein to Life

I would use even so:

Nevertheless, still, that being the case.

Or just use nevertheless.

This expresses the contrast between "easy to use" and "expressive and powerful enough".

So:

In this paper, we propose a wrapper generation system for extracting main content from web pages which is easy to use and understand by an average user. Even so, it is expressive and powerful enough to cover most tasks in content extraction scenarios.

I would not use time phrases since you are describing qualities, not actions.