If you will need many records from Lenk, then this is probably a good idea. At least, the quality of the CDs of those four municipalities should be much better than the quality of the Scans at State Archive Bern.
If you need only very few records, you can ask in geneal-forum, under "Bern (BE)", if someone has the CD and would do a look-up.
New topics should be named "*surname* von *Heimatort* BE". You can write in English, maybe attach a translation with DeepL.com .