Resize gallery items and avoiding cut items

Hello

I want to congratulate you for this plugin; I am currently developing an art gallery and need to categorize many artworks by the years: this plugin really does fit!

I created a filterable gallery and placed its shortcode in a block. For each year (which is a category), a three-columns gallery is shown (on each row, there are three images showing the same artwork by three different points of view) filtered according to the year, but there are two issues: first, each image in the gallery is always cut on their right side, even reducing the div size that contains the image; second, in Edit Gallery, I have to set Item Columns to 4 Columns in order to have three items on each row!

Hope you can give me useful hints to solve my problems. This is the simplest and clearest plugin I found to design my art gallery and I want to use it!

Thank you