At B2, students can use the form: adjective + but + adjective + noun.
In the English Grammar Profile, point 45 in the category of NOUNS is defined as:
increasing range of complex noun phrases with more than one adjective combined with ‘but’.
Here’s an iWeb corpus frequency list of the most common combinations of ‘adjective + but + adjective + noun’ and some expert examples.
_JJ but _JJ _NN
1 SERIOUS BUT STABLE CONDITION 534
Two officers on the train were violently confronted by the crowd,
and tonight are in serious but stable condition at Gotham Metropolitan.
2 CRITICAL BUT STABLE CONDITION 458
3 SMALL BUT GROWING NUMBER 438
4 SIMPLE BUT EFFECTIVE WAY 357
5 MOIST BUT WELL-DRAINED SOIL 220
6 SLOW BUT STEADY PROGRESS 135
7 RARE BUT SERIOUS SIDE 132
8 SMALL BUT SIGNIFICANT NUMBER 128
9 SMALL BUT VOCAL GROUP 126
10 SLOW BUT STEADY GROWTH 119
11 SMALL BUT DEDICATED GROUP 114
12 ACCRUED BUT UNPAID INTEREST 108
13 SMALL BUT GROWING GROUP 108
14 SMALL BUT IMPORTANT PART 100
15 SUBTLE BUT IMPORTANT DIFFERENCE 97
16 SERIOUS BUT NON-LIFE-THREATENING INJURIES 96
17 SMALL BUT SIGNIFICANT CHANGES 94
B2 vocabulary found in this complex noun phrase includes:
critical, effective, growth, injuries, significant, soil, steady, threatening