I mentioned it in the podcast, you are right. The statement is correct. The conveyance is in error. There is a SpeedCheck, but not for the Atari. It was indeed in Compute! Gazette, not Compute!.
I spoke of it in the background section where I was talking about the programs history, and some of the other platforms. From my notes of that podcast which was just over 5 years ago now (2016):
-Jan 1984 Version 1 for C64 and VIC20.
-1.1 published in Computes 2nd book of Commodore.
-May 84 saw 2.0 in Gazette Disk.
-March and April 85 3.0 released in Compute! magazine.
-May 85 3.1 corrections published. 3.1 full published in stand alone book Compute! SpeedScript: The Word Processor for the Commodore 64 and Vic-20.
-May 1985, ported to Atari 8.
-June 1985, ported to Apple II.
-December 85 and Jan 86 published 3.2 update.
-December 85 also saw the release of SpeedCheck in Compute! Gazette. Checked docs against user defined dictionary. Also checked docs from word processors like PaperClip.
-June 86, SpeedScript 80 to support Commodore 128 80 column video, but worked in C64 mode and didn’t support extra memory. It was updated by Bob Kodadek to support the memory and was called SpeedScript 80 Revisited.
-May 87, Computes Gazette re-published 3.2 with 3 utilities: ScriptRead which could identify and preview SpeedScript docs on disk with ability to delete them; SpeedSearch which was a word count utility (think Unix wc); and Date & Time Stamper, which would allow timestamping of files.
-October 1987, Bob Kodadek released SpeedScript 128 which was a C128 native version which also supported the C128 enhanced keyboard.
-December 1987, Compute! released Instant 80 for C64 which allowed viewing only of SpeedScript docs in 80 column mode on standard C64.
-1988 a port to PC’s running MS-DOS done by Randy Thompson, published by Compute! Books. Written in Turbo Pascal, with parts in Assembly.
-September 1988, SpeedCheck 128 was released to support C128.
-September 1989, Bob Kodadek further revised SpeedScript 128 to have full text justification, tab setting and online help
Perhaps I could have been clearer to which platforms the programs and versions existed. The Atari didn't reap all the benefits of the other Commodore platform.