Has the RT licence to be carried or not?
 

Not really sure where to post this question, but this seems to be the section that fits it most.

Am I required to carry my RT licence with my pilot licence and medical certificate or not?
I thought it is mandatory but someone told me I don't have to as it is also stated on my licence that I have demonstrated competence to operate the equipment. And it would make sense as I don't carry my language proficiency around, it is printed on my licence.

Just want to be sure and avoid going against any regulations.

It' sreally going to depend on what regulations apply in the State which issues your licence, the rules that apply to documentation that must be carried on an aircraft (which, I think, sometimes extends to the qualifications of the operating crew) set by the State of registry, and then the rules that apply to crews in the the airspace in which you will be flying set by the State whose airspace it it.

Do you keep your licence, medical and RT certificates in different places? If so then I understand your dilemma.

What licence do you have? The separate FRTOL is no longer issued to holders of EASA and National licences as it is included in section XII of the pilot licence.

EASA PPL (in modular training) issued by the Polish CAA, and no, I keep my licence, medical and RT certificate in one place. However, the latter won't enter in my licence holder.