So, I just replaced my Galaxy S8 with a Galaxy S10, and this problem has not been fixed. If you care at all about your punctuation not being messed up when you do an import, then you still have to manually edit your exported .vzm files to find and replace the messed up string as described above.
Furthermore, if you have a lot of text messages (like I do, partly for business reasons), then it's hit or miss whether Message+ will even do the import - at least on my new S10. In prior versions of the app, it would hang up when exporting many messages, but you could get around this by selecting and exporting a few conversations at a time and then separately restoring each exported file. Now exports seem to work well, and fast. But the import process is flaky. Sometimes when you select the conversation to import "from SD card "(which really looks at the internal storage NOT at an external SD card), often nothing will happen and you'll see a notification on the phone that says "Restore Canceled" even though you didn't cancel it. If you long-press on the conversation you want to restore though, and press the restore option, it'll usually start. But then the progress notification you get on the phone will completely hang up partway through the restore, and you have no way of knowing when or if the process actually completes. Of course, even if it does complete, you'll end up with garbled apostrophes if you didn't manually edit your .vzm file(s) before restoring from them