Room temperature --at least in the UK-- will never give you a butter soft enough to cream with sugar. So most recipes call now for softened or spreadable butter.
Spreadable butter, however, is a type of butter. Examples below.

Ingredients
200g caster sugar
200g softened butter
4 eggs, beaten
https://www.bbcgoodfood.com/recipes/1997/classic-victoria-sa...

NGREDIENTS
250g butter, softened
1 cup caster sugar
2 teaspoons vanilla essence
https://www.taste.com.au/recipes/butter-cake/6dd26828-d6f3-4...


INGREDIENTS
115g self-raising flour
1 level teaspoon baking powder
115g spreadable butter
https://www.deliaonline.com/recipes/type-of-dish/cake-recipe...

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Note added at 3 hrs (2018-08-13 08:24:34 GMT)
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¨Pomada¨or ¨softened¨are more specific than ¨room temperature¨, which varies greatly depending on your location and season.

WHEN BUTTER SHOULD BE SOFTENED (SLIGHTLY COOLER THAN ROOM TEMP)
In general, butter should be softened when it is going to be creamed with sugar. The ideal temperature for butter that will be creamed is 68-70F. Many times, since most kitchens are hotter than 70F, butter is allowed to become too warm before the creaming process. Remember, butter is completely liquid at 90-95F, so even at 80F it is starting to get too soft.

Softened butter in baking is creamed together with sugar to aerate it before the rest of the ingredients are added. The process of beating the butter and sugar together creates this whole network of fat, sugar, and air. This helps to leaven your baked good and creates a more fluffy and tender product.
https://bakerbettie.com/function-of-butter-in-baking/#When_B...