A newer version of UltraEdit can load macros created by an older version of UltraEdit as long as there is no bug in internal macro converter. But a macro created with a newer version of UltraEdit cannot be loaded by an older version of UltraEdit which stores macros with a different internal structure and macro version. UltraEdit v16.00 cannot load macros created by UltraEdit v24.00 or any later version because of macro extensions for full Unicode support in macros.

There is no built-in command or extra tool to convert macro of a newer version as much as possible to an older macro version.

Here are the steps for a manual "conversion" in case of UE v25.00 and v16.00 are installed on same computer and can be started at the same time to run parallel.

1. Start UE v25.00 and load the macro file.
2. Start UE v16.00 in addition to UE v25.00 and click in menu Macro on menu item Edit Macro.
3. In UE v25.00 click on ribbon tab Advanced in third group Macro on down arrow right to Configure and click in pop-up menu on Configure macros.
4. For current macro listed in Modify Macro dialog in UE v25.00 click on button Rename, press Ctrl+C to copy the macro name and click on button Cancel. Then switch to UE v16.00, click on button New Macro, press Ctrl+V to paste the macro name and check the options as shown in Modify Macro dialog of UE v25.00 for this macro and enter the hotkey in UE v16.00 as shown in UE v25.00 for this macro. Then click on button OK in UE v16.00 to create that new macro.
5. Repeat step 4 for all macros listed in UE v25.00.
6. In UE v25.00 click on button Cancel to close the Modify Macro dialog.
7. Next click on ribbon tab Advanced in third group Macro on down arrow right to Configure and click in pop-up menu on Edit macro....
8. Select from list at top the first/next macro in list in UE v25.00, select entire macro code, press Ctrl+C, select in UE v16.00 the same macro, select entire macro code and press Ctrl+V to overwrite selected code by the copied code. Select the next macro in list at top in UE v16.00 and confirm updating the current macro.
   Important: Macro editor of UE v25.00 escapes a " and sometimes also \ with an additional \. You have to remove those escaping backslashes in code in macro editor of UE v16.00. See this post for the reason and details of different encoding of " and sometimes also \ in UE v25.00 in comparison to all former versions of UltraEdit.
9. Repeat step 8 for each macro in UE v25.00.
10. Close in both UltraEdit the Edit/Create Macro dialog and click in UE v16.00 in menu Macro on menu item Save All... and save all the macros into a macro file.

Here are the steps for a manual "conversion" in case of UE v25.00 and v16.00 are not installed on same computer.

1. Start UE v25.00 and load the macro file.
2. Click on ribbon tab Windows in last group Application on last item New instance to start a second instance of UltraEdit v25.00 and open in this second instance a new file.
3. In first instance click on ribbon tab Advanced in third group Macro on down arrow right to Configure and click in pop-up menu on Configure macros.
4. For current macro listed in Modify Macro dialog in first instance click on button Rename, press Ctrl+C to copy the macro name and click on button Cancel. Then switch to second instance, press Ctrl+V to paste the macro name into the text file and write into text file also check states of the two macro properties as well as the assigned hotkey.
5. Repeat step 4 for all macros listed in first instance.
6. In first instance click on button Cancel to close the Modify Macro dialog.
7. Next click on ribbon tab Advanced in third group Macro on down arrow right to Configure and click in pop-up menu on Edit macro....
8. Select from list at top the first/next macro in list in first instance, select entire macro code, press Ctrl+C, switch to second instance, navigate in text file to appropriate macro name and press Ctrl+V to paste the copied macro code.
   Important: Macro editor of UE v25.00 escapes a " and sometimes also \ with an additional \. You have to remove those escaping backslashes in macro code for UE v16.00. See this post for the reason and details of different encoding of " and sometimes also \ in UE v25.00 in comparison to all former versions of UltraEdit.
9. Repeat step 8 for each macro in first instance.
10. Save the text file in second instance, close the file and exit second instance.
11. Close in first instance the Edit/Create Macro dialog.
12. Transfer the text file with all macro names, macro properties, macro hotkeys and macro code blocks to computer with UltraEdit v16.00.
13. Start two instances of UltraEdit v16.00 and open in one instance the text file and in other instance the Edit/Create Macro dialog, create all the macros with appropriate name, check box properties, hotkey and macro code and finally save all the macros into a macro file.

For the next time I suggest to record macros with UE v16.00 because of UE v25.00 has no problem to load a macro file created with UE v16.00. UE v25.00 does not even modify the binary data stored in *.mac file on loading the macro file because of macro conversion is done on load just in memory. The macro file itself is only modified by UE v25.00 on saving all currently loaded macros into that macro file. Then this macro file cannot be loaded anymore with eight year older UE v16.00 not supporting Unicode and some macro commands introduced with later versions of UltraEdit.

By the way: Many of your macros can be replaced by (global/language) templates which can be also executed by key. That's how I use such HTML snippets.