How to add a Font to a pdf using PDFGen in C

Context:
I’m working on a program that will generate PDF files from a set of images.
I’m using this library: https://github.com/AndreRenaud/PDFGen.

Problem:
I want to use Calibri-Bold as the font of each PDF cover page, everything works fine except when I open the output.pdf file there is an error “The font ‘Calibri-Bold’ contains a bad /BBox” and the letters aren’t spaced correctly.

Code:

#include "pdfgen.h"

int main(void) {
    struct pdf_info info = {
            .creator = "",
            .producer = "Band'a la Page",
            .title = "Piccolo book",
            .author = "Theo SARDA",
            .subject = "Band'Ales book for Piccolo",
            .date = "Today"
    };
    struct pdf_doc *pdf = pdf_create(PDF_A6_HEIGHT, PDF_A6_WIDTH, &info);
    pdf_set_font(pdf, "Calibri-Bold");
    pdf_append_page(pdf);
    float x() = {PDF_MM_TO_POINT(0), PDF_MM_TO_POINT(80), PDF_MM_TO_POINT(100), PDF_MM_TO_POINT(60), PDF_MM_TO_POINT(0)};
    float y() = {PDF_MM_TO_POINT(0), PDF_MM_TO_POINT(0), PDF_MM_TO_POINT(70), PDF_MM_TO_POINT(105), PDF_MM_TO_POINT(105)};

    pdf_add_filled_polygon(pdf, NULL, x, y, 5, 0, PDF_ARGB(0xFF, 0xC0, 0x00, 0x00));
    pdf_add_text(pdf, NULL, "Carnet Piccolo", 12, 30, 30, PDF_WHITE);
    //pdf_add_line(pdf, NULL, 50, 24, 150, 24, 3, PDF_BLACK);
    pdf_save(pdf, "output.pdf");
    pdf_destroy(pdf);
    return 0;
}

Result:
Screeshot