It has been possible for quite some time now to choose which Glossary pane layout to use in OmegaT. Selection isn’t that great, only two layouts are provided: Default and Dictionary. But at the same time this feature had been introduced, it became possible to add custom layouts via plugins. I haven’t seen any, but the possibility is there. And just recently, Hiroshi Miura, a very prolific OmegaT developer, published a plugin skeleton just for this purpose. I used what he generously shared, and made an alternative compact layout for the Glossary pane.
It puts target terms right after the source term on the same line, and separates them only by a vertical bar and spaces. If there’s a comment for the term, it follows it immediately enclosed in square brackets. If OmegaT is set up to merge multiple target definitions for the same source term, and there are duplicated entries (i.e. two or more identical target terms for the same source term) with different comments, the comments will be separated by the vertical bar, but the term itself won’t be repeated.
To enable this layout in OmegaT, download the plugin (the ready-to-use jar is in the Releases section), put it into
plugins subfolder in your OmegaT config folder, restart OmegaT, and select it under Preferences → Glossary → Glossary layout: → Compact Glossary Layout