can u try with other libraries like "ReportLab" or "pdfrw"?
for text inserstions can u try this?
page.insert_text((x_start + 5, y_start + 5), char, fontsize=12, color=(0, 0, 0))
also using "draw_text" method
page.draw_text((x_start + 2, y_start + 2), char, fontsize=12, color=(0, 0, 0))