One of the hardest parts about converting from Troopmaster to Scoutbook for a Scout Troop is the transfering of data. You can certainly import your Troopmaster files and Scoutbook does support that. It seems that you have far greater control over your data (and I think it's also faster) if you import the data in the csv format expected by Scoutbook.
Scoutbook provides a primer for doing this import, including sample files here: https://www.scoutbook.com/mobile/forums/frequently-asked-questions/3852/scoutbook-csv-data-import/
The scripts in this repository represent many hours of trial and error on getting data out of Troopmaster and massaging it into the right format for Scoutbook. Due to the way that Troopmaster can be "customized" some of the choices made by the scripts may not work properly for your unit. You should treat this as a starting point and adjust as necessary. I wish I could provide a turnkey solution but there are just too many different combinations to make that feesible.
Here are the steps necessary to export your data from Troopmaster:
File -> Export -> ASCII Delimited...
Scout.txt file: Check Include field names as first line of export Format: Comma delimited Select area: Scout Data Date Format: MM/DD/YYYY Members: All Scouts Click "Add All>>"
Export
Adult.txt file: Check Include field names as first line of export Format: Comma delimited Select area: Adult Data Date Format: MM/DD/YYYY Members: All Adults Click "Add All>>"
Export
Reports: Reports -> Activities -> Individual Activities...
Display Level: All Levels
Display Types: All Activity Types
Select All Activities
Check: Include scout attendance
Un-Check: Include adult attendance
Select
Save as Text report
You should utilize ScoutNET for all completed advancement and training records. If you aren't using Internet Advancement, now is an excellent time to start.
scout.py Parse the exported scout data file into something appropriate for Scoutbook.
adult.py Parse the exported adult data file into something appropriate for Scoutbook.
parse_activity_report.py Parse the activity report into something appropriate for Scoutbook.