I think all the mentioned issues should now be fixed.

I checked some of the source files, and it turns out they say permit any later version of the license, so I changed the license to lgpl3+.

Only the README file mentions "just" LGPLv3 without saying anything about later versions, so I thought it meant the same as "only".

Here's the new patch in git format:

From 97d4d5d7d16eb87896d81e070510d919118aa622 Mon Sep 17 00:00:00 2001
From: Riku Viitanen <riku.viitanen0@gmail.com>
Date: Wed, 18 Dec 2019 18:30:14 +0200
Subject: [PATCH] gnu: Add glyr

* gnu/packages/music.scm (glyr): New variable
---
 gnu/packages/music.scm | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/gnu/packages/music.scm b/gnu/packages/music.scm
index f80fb067e8..0adfa96fbe 100644
--- a/gnu/packages/music.scm
+++ b/gnu/packages/music.scm
@@ -25,6 +25,7 @@
 ;;; Copyright © 2019 raingloom <raingloom@protonmail.com>
 ;;; Copyright © 2019 David Wilson <david@daviwil.com>
 ;;; Copyright © 2019 Alexandros Theodotou <alex@zrythm.org>
+;;; Copyright © 2019 Riku Viitanen <riku.viitanen0@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -5106,3 +5107,37 @@ MIDI drums and comes as two separate drumkits: Black Pearl and Red Zeppelin.")
     (description "Helm is a cross-platform polyphonic synthesizer available standalone
 and as an LV2 plugin.")
     (license license:gpl3+)))
+
+(define-public glyr
+  (package
+    (name "glyr")
+    (version "1.0.10")
+    (source (origin
+              (method git-fetch)
+              (uri (git-reference
+                     (url "https://github.com/sahib/glyr.git")
+                     (commit version)))
+              (file-name (git-file-name name version))
+              (sha256
+                (base32
+                 "1miwbqzkhg0v3zysrwh60pj9sv6ci4lzq2vq2hhc6pc6hdyh8xyr"))))
+    (build-system cmake-build-system)
+    (arguments
+     '(#:tests? #f))
+    (inputs
+     `(("glib" ,glib)
+       ("curl" ,curl)
+       ("sqlite" ,sqlite)))
+    (native-inputs
+     `(("pkg-config" ,pkg-config)))
+    (home-page "https://github.com/sahib/glyr")
+    (synopsis "Search engine for music related metadata")
+    (description
+     "Glyr comes both in a command-line interface tool (@command{glyrc}) and
+as a C library (libglyr), both with an easy to use interface. The sort of
+metadata glyr is searching (and downloading) is usually the data you see in
+your musicplayer. And indeed, originally it was written to serve as internally
+library for a musicplayer, but has been extended to work as a standalone
+program which is able to download cover art, lyrics, photos, biographies,
+reviews and more.")
+    (license license:lgpl3+)))
--
2.24.1