Get the local climbing guidebook from Refugio Tisá, HUDY Hřensko possibly also from the local camp. Two options available:
TOPO guide in German and English, 2020 uses standardized saxon grading system wherever the grade is known (marked with "RP"). If no "RP" is written, only the JPK grading is known and you may expect anything.
Průvodce Ostrov, standard czech text guide, 2021, Pay special attention as it uses the traditional JPK grading system (see grading in description).