Display of bold characters unreadable

まず、報告された Custom-Metrics-24 フォントを使用する PDF で Xreader 2.2.3 上の問題を再現し、同じファイルを Foxit Reader で開いた場合の太字の描画と比較します。ソースファイルやテストは指定されていません。影響を受ける太字の文字が読みやすく、太字のまま表示され、説明されている PDF のバリエーション全体で動作が検証されれば完了です。

 * Xreader version 2.2.3
 * Distribution - Mint Cinnamon 19.2 LTS, Linux kernel 4.15.0-123-lowlatency.

Issue
Display of bold characters is nearly unreadable in a bank produced PDF report. Bold style makes the characters blurry and character lines are too big which hides white space. For example, a character 6 and a character 8 have no white space in the circle that make the characters.

Verified multiple PDF files.

1. Many PDF files with the problem had the following characteristics, from XReader "File | Properties" menu:
   a. Producer = 303l AIX (64bit)
   b. Creator = Ricoh Production Print Solutions Afp2Pdf Version: 303l
   c. Format = PDF-1.3
   d. Optimized = No
   e. Security = No
   f. Fonts = Custom-Metrics-24; and others. --> NOTE: a previous bank report with "Custom-Metrics-23" instead of "Custom-Metrics-24" displays well.

Other bank reports with the same combination of Producer, Creator, Format, Security, and Optimized values display well. Others with Optimized = Yes also display well. However, the fonts differ.

2. One PDF file with the problem had the following characteristics, from XReader "File | Properties" menu:
   a. Producer = Ricoh Americas Corporation, AFP2PDF Plus Version: 1.200.21, AIX
   b. Creator = Ricoh Americas Corporation, AFP2PDF Plus Version: 1.200.21
   c. Format = PDF-1.4
   d. Optimized = Yes
   e. Security = No
   f. Fonts = Custom-Metrics-24; and others. --> NOTE: Other bank reports with mainly "C0EX0....afm" fonts instead of a combination of different fonts ("C0A....afm", "C0D....afm", and other) display well.

Other bank reports with the same combination of Producer, Creator, Format, Security, and Optimized values display well. However, the fonts differ.

Steps to reproduce
Open a PDF file with the characteristics described above from Nemo file manager, using default XReader.

Expected behaviour
Bold characters should be readable.

Other information
a. Bold characters in the same PDF files are very readable, as expected, while remaining bold using Foxit Reader version 9.72 on a Windows 7 computer.
b. Bold characters in other reports from the same bank display correctly, format "PDF-1.4", Producer = "iText® 5.4.3 ©2000-2013 1T3XT BVBA (AGPL-version)" OR "iText® 5.4.1 ©2000-2012 1T3XT BVBA (AGPL-version)".