[Gilles Pialat]

Unfortunately, there is no way to preview fx when adding fx in Media Pool.
I made several time a product suggestion

[Gilles Pialat]

I saw the same thing when I tried to change Vegas language.
Have a look at the registry key :
HKEY_LOCAL_MACHINE\SOFTWARE\Sony Media Software\Vegas\7.0\Lang

Make sure the UlangID is set to 409 (default for English).

Since V7.0b the UlangID can be set to:
40C for French
411 for Japan
407 for German

If I set this value to 40D, I get the same phenomenon as you.

[Gilles Pialat]

Menu Options > Preferences > Burning > Temporary files folder

Choose another folder on a bigger HD.

[Gilles Pialat]

Another one for multiple color pass (in french):
https://www.cameravideo.net/fr/news-et-articles/article/effet-color-pass-multiple.html

[Gilles Pialat]

No overwrite mode
No track lock button
No Mpeg smart rendering
Prerender file management is disastrous

[Gilles Pialat]

Right clic transition > Insert/Remove envelope > Transition progress.

[Gilles Pialat]

Set your preview quality to

[Gilles Pialat]

Go to : https://www.custcenter.com/cgi-bin/sonypictures.cfg/php/enduser/std_alp.php
And make a search with

[Gilles Pialat]

I will be glad to try your plugins.
I often work with music band (video clip & mastering)

Gilles (from France)

[Gilles Pialat]

Try Ctrl+Shift+End (or Ctrl+Shift+Home)