Pls modify the shortcode like below –
[project_showcase blog_tab_text="Senaste inlägg" portfolio_tab_text="recent work"][/project_showcase]
If you do not need the portfolio tab, I would advise you to use the below shortcode since tab function will not be useful when you have just one list to show –
[show_post_snippets post_type="post" number_of_columns=4 post_count=4 image_size="medium" show_meta=true excerpt_count=50 display_text=true]